Bertrand's Postulate

It began with a question: Are any Factorials an Exact Power?

(The factorial of n is the product of all natural numbers less than or equal to n. An exact power is an n = m^s for natural numbers m,s>1.)

Well? Guess first before we do any thinking. But guess No. Because anything else should make the maths part of your brain sad and hurt.

So no. But also no, there won't be any thinking here. In that way lies unhealth and it's far too hard anyways. Rather, the modern tenor must be embraced. 'The Computer' shall do our thinking for us. This below runs out prime factor decompositions of some early factorials.

/**
 * Class to examine the powers of factorials.
 */
import java.util.Arrays;

/**
 * Print prime decomposition profiles for early factorials
 */
public class FactorialPowers
{
   /**
    * Short primes list for testing. Primes < 100
    */
   private static final int[] PRIMES = { 2, 3, 5, 7, 11, 13, 17, 19, 23, 29,
      31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97 };

   /**
    * @param args unused
    */
   public static void main(String[] args)
   {  // We build the factors of n! from (n-1)! and n. So we want to be
      // keeping a tally of the primes seen each time through our loop.
      // factors[i] is the power of PRIMES[i] in the prime decomposition
      // of n! (Loop Invarient across all the indices)
      int[] factors = new int[PRIMES.length];

      // We start looping with the prime decomposition of 1, no prime factors.
      // for (int i = 0; i < factor.length; i++) { factors[i] = 0; }

      // For each factorial we are sure we can properly factor...
      // i.e. as far as our last prime. Can go last prime +1 but not +2 since
      // that itself can be prime and not already in our list.
      // <= because we can go as far as the last prime okay.
      System.out.println("Primes" + Arrays.toString(PRIMES));
      for (int n = 2; n <= PRIMES[PRIMES.length - 1]; n++)
      {  // We have already factorised (n-1)! so just add the factors of n.

         // Run though our primes less than n pulling out factors,
         // breaking down n as we go until it is 1.
         int i = 0;
         int n_ = n;
         while (n_ > 1)
         {  // Is the i-th prime a factor of n_? If so add it to factors,
            // break down n_ and reenter the loop to test the i-th prime
            // for a repeated factor
            if (n_ % PRIMES[i] == 0)
            {  factors[i]++;
               n_ /= PRIMES[i];
            }
            else // Otherwise step on to testing the next prime.
            {  i++;
            }

            // Some sanity...
            // CAN'T HAPPEN: Our i-th PRIME exceeds n_ and we're not already done
            assert (!(PRIMES[i] > n_ && n_ != 1));
            // TEST: The i index should be in bounds or we're already done.
            assert (i < PRIMES.length || n_ == 1);
         }

         // Dump the computed factors to the console.
         System.out.println(n + "! : " + Arrays.toString(factors));
      }
   }
}


[Sigh. I bet that's incorrectly sized. What a drag. But look, I tried, okay.]

An exact power isn't too hard to spot from a prime decomposition. All the powers should be divisible by some common number greater than 1. A really easy case if is all the powers are the same, for instance. But you may have a case where all the powers are 2 say, except for the power on one prime which might be 4 perhaps. That's still an exact power because the prime, p, which is raised to the fourth power is still a square, only of itself squared, p^2. Because of (p^2)^2 = p^4. So we're looking to find a prime decomposition powers sequence with a nontrivial(I'd say decent) highest common factor.

Now so, what does 'The Computer' say when this is run...

First it tells us what primes it is worrying with.
Primes[2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97]
And then it tells us a bunch of happy decompositions.
2! : [1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
Because 2! = 2. Nicely.
3! : [1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
Because 3! = 2 * 3. Isn't this computer clever?
4! : [3, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
Because 4! = 2 * 3 * 4 = 2 * 3 * (2 * 2) = 2^3 * 3. And blah and blah for...
5! : [3, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
6! : [4, 2, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
7! : [4, 2, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
8! : [7, 2, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
9! : [7, 4, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
10! : [8, 4, 2, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
11! : [8, 4, 2, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
12! : [10, 5, 2, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
13! : [10, 5, 2, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
14! : [11, 5, 2, 2, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
15! : [11, 6, 3, 2, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
16! : [15, 6, 3, 2, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
17! : [15, 6, 3, 2, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
18! : [16, 8, 3, 2, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
19! : [16, 8, 3, 2, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
20! : [18, 8, 4, 2, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
21! : [18, 9, 4, 3, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
22! : [19, 9, 4, 3, 2, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
23! : [19, 9, 4, 3, 2, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
24! : [22, 10, 4, 3, 2, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
25! : [22, 10, 6, 3, 2, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
26! : [23, 10, 6, 3, 2, 2, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
27! : [23, 13, 6, 3, 2, 2, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
28! : [25, 13, 6, 4, 2, 2, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
29! : [25, 13, 6, 4, 2, 2, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
30! : [26, 14, 7, 4, 2, 2, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
31! : [26, 14, 7, 4, 2, 2, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
32! : [31, 14, 7, 4, 2, 2, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
33! : [31, 15, 7, 4, 3, 2, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
34! : [32, 15, 7, 4, 3, 2, 2, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
35! : [32, 15, 8, 5, 3, 2, 2, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
36! : [34, 17, 8, 5, 3, 2, 2, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
37! : [34, 17, 8, 5, 3, 2, 2, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
38! : [35, 17, 8, 5, 3, 2, 2, 2, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
39! : [35, 18, 8, 5, 3, 3, 2, 2, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
40! : [38, 18, 9, 5, 3, 3, 2, 2, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
41! : [38, 18, 9, 5, 3, 3, 2, 2, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
42! : [39, 19, 9, 6, 3, 3, 2, 2, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
43! : [39, 19, 9, 6, 3, 3, 2, 2, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
44! : [41, 19, 9, 6, 4, 3, 2, 2, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
45! : [41, 21, 10, 6, 4, 3, 2, 2, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
46! : [42, 21, 10, 6, 4, 3, 2, 2, 2, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
47! : [42, 21, 10, 6, 4, 3, 2, 2, 2, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
48! : [46, 22, 10, 6, 4, 3, 2, 2, 2, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
49! : [46, 22, 10, 8, 4, 3, 2, 2, 2, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
50! : [47, 22, 12, 8, 4, 3, 2, 2, 2, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
51! : [47, 23, 12, 8, 4, 3, 3, 2, 2, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
52! : [49, 23, 12, 8, 4, 4, 3, 2, 2, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
53! : [49, 23, 12, 8, 4, 4, 3, 2, 2, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0]
54! : [50, 26, 12, 8, 4, 4, 3, 2, 2, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0]
55! : [50, 26, 13, 8, 5, 4, 3, 2, 2, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0]
56! : [53, 26, 13, 9, 5, 4, 3, 2, 2, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0]
57! : [53, 27, 13, 9, 5, 4, 3, 3, 2, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0]
58! : [54, 27, 13, 9, 5, 4, 3, 3, 2, 2, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0]
59! : [54, 27, 13, 9, 5, 4, 3, 3, 2, 2, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0]
60! : [56, 28, 14, 9, 5, 4, 3, 3, 2, 2, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0]
61! : [56, 28, 14, 9, 5, 4, 3, 3, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0]
62! : [57, 28, 14, 9, 5, 4, 3, 3, 2, 2, 2, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0]
63! : [57, 30, 14, 10, 5, 4, 3, 3, 2, 2, 2, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0]
64! : [63, 30, 14, 10, 5, 4, 3, 3, 2, 2, 2, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0]
65! : [63, 30, 15, 10, 5, 5, 3, 3, 2, 2, 2, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0]
66! : [64, 31, 15, 10, 6, 5, 3, 3, 2, 2, 2, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0]
67! : [64, 31, 15, 10, 6, 5, 3, 3, 2, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0]
68! : [66, 31, 15, 10, 6, 5, 4, 3, 2, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0]
69! : [66, 32, 15, 10, 6, 5, 4, 3, 3, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0]
70! : [67, 32, 16, 11, 6, 5, 4, 3, 3, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0]
71! : [67, 32, 16, 11, 6, 5, 4, 3, 3, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0]
72! : [70, 34, 16, 11, 6, 5, 4, 3, 3, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0]
73! : [70, 34, 16, 11, 6, 5, 4, 3, 3, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0]
74! : [71, 34, 16, 11, 6, 5, 4, 3, 3, 2, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0]
75! : [71, 35, 18, 11, 6, 5, 4, 3, 3, 2, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0]
76! : [73, 35, 18, 11, 6, 5, 4, 4, 3, 2, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0]
77! : [73, 35, 18, 12, 7, 5, 4, 4, 3, 2, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0]
78! : [74, 36, 18, 12, 7, 6, 4, 4, 3, 2, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0]
79! : [74, 36, 18, 12, 7, 6, 4, 4, 3, 2, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0]
80! : [78, 36, 19, 12, 7, 6, 4, 4, 3, 2, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0]
81! : [78, 40, 19, 12, 7, 6, 4, 4, 3, 2, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0]
82! : [79, 40, 19, 12, 7, 6, 4, 4, 3, 2, 2, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0]
83! : [79, 40, 19, 12, 7, 6, 4, 4, 3, 2, 2, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0]
84! : [81, 41, 19, 13, 7, 6, 4, 4, 3, 2, 2, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0]
85! : [81, 41, 20, 13, 7, 6, 5, 4, 3, 2, 2, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0]
86! : [82, 41, 20, 13, 7, 6, 5, 4, 3, 2, 2, 2, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0]
87! : [82, 42, 20, 13, 7, 6, 5, 4, 3, 3, 2, 2, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0]
88! : [85, 42, 20, 13, 8, 6, 5, 4, 3, 3, 2, 2, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0]
89! : [85, 42, 20, 13, 8, 6, 5, 4, 3, 3, 2, 2, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0]
90! : [86, 44, 21, 13, 8, 6, 5, 4, 3, 3, 2, 2, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0]
91! : [86, 44, 21, 14, 8, 7, 5, 4, 3, 3, 2, 2, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0]
92! : [88, 44, 21, 14, 8, 7, 5, 4, 4, 3, 2, 2, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0]
93! : [88, 45, 21, 14, 8, 7, 5, 4, 4, 3, 3, 2, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0]
94! : [89, 45, 21, 14, 8, 7, 5, 4, 4, 3, 3, 2, 2, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0]
95! : [89, 45, 22, 14, 8, 7, 5, 5, 4, 3, 3, 2, 2, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0]
96! : [94, 46, 22, 14, 8, 7, 5, 5, 4, 3, 3, 2, 2, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0]
97! : [94, 46, 22, 14, 8, 7, 5, 5, 4, 3, 3, 2, 2, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1]

The engineer in all of us now declaims that the power of the highest prime in the decomposition of any factorial is 1. So there can't be an exact power n! = m^s with m,s>1. Because we must group up all the prime factors of n! to give the m if it exists. However the top prime won't ever be a square or higher power. So we won't be getting our s>1. Tough sh*t, really.

All very helpful, thank you Mr. Computer. It's useful having you around when we don't have a brain of our own. Still, it nags. How should we have seen this originally if we were proper clever?

The answer, of course, is Bertrand's Postulate. A fantastic piece of magic which I shall salute with my first pint of the evening later. In fact, you should always be thinking Bertrand's Postulate because it is the quick jackknife punch in the stomach for getting out of dark elementary number theory alleys.

Now it says there's always a prime between n and 2n for n>1. So suppose the top prime, p, of our factorial is a square. (Or any higher power because cubes have squares in them, etc.) Then what happened to the prime, q, the one between p and 2p. It is larger than p but smaller than 2p. And if p^2 is in the prime decomposition of n! then n>=2p for how else is it to sweep up the doubled prime except with the p and 2p parts of the factorial multiplications at best.

This leaves us with p the top prime in n! and n >= 2p > q > p. Meaning q is one of the terms in n! only it is not top prime despite being prime and larger that the top prime p. Which is all bogus.

It's great not having to think, isn't it?

Only is it? The great fear is of compthink groupthink. Has the computer tended us to a particular solution? One which doesn't speak to the real essence of the problem?

Computer lead investigations have a natural computational flavour. Because that's what they are, computational. But a computational proof is an unseemly thing at times. They can be arithmeticisms and not mathematicisms. Mathematics wants 'real solutions' to questions, the solutions which enlighten and inform. And only occassionally are these computational style.

But now the pedagogy of this example goes missing. Hey, don't hassle me, I didn't cook it up to straw man a moral position. The highest prime is critical to deciding that factorials are never exact powers. You are basically stuck with finding it a pairing factor to sweeten out into a power. And you'll only get that factor from higher up the factorial product. But we know that by the time you get to that factor, the stuff in between will have messed in a way that puts you back where you started. Namelu, looking for a complement to a new highest prime.

For sure? Isn't there maybe some other explanation at play? Well, look at the decomposition of 10!. It's:
10!=2.3.4.5.6.7.8.9.10=2.3.(2^2).5.(2.3).7.(2^3).(3^2).(2.5)
And we rearrange to get 10! = (2^8).(3^4).(5^2).7 and here our only problem is the highest prime, 7. The rest is:
(2^8).(3^4).(5^2)=(2^4.3^2.5)^2=720^2
So yeah, this is a case where the bottom stuff all sorts itself out and only the top prime causes grief.

Extra Credit: The decomposition profiles seem to grow strings of ones on the top side. Is this for sure? Will the number of single power primes at the top of a factorial prime decomposition grow arbitrarily large or is it gonna happen that they will shrink? And if they collapse to a single one, can all the factors but the top prime sort themselves into a convenient square or higher power arbitrarily often?

Mercurialism & Mercurists

Been too much fascinatingly and enlighteningly in the Mercur- section of the OED lately. Oh, the quality of word from that market, godlike and chemical root! Sic vita humana. And if that doesn't convince you, the 8 January calendar entry said 'Pia fraus'.

But bystanding mercies(teehee) I've a new favourite word home. Like 'mercurial', where some rare noun usages inform my sense of the common adjective. Mercurials, indeed! And yet more evidence for my OED Law. All words possess unexpected obscure usages in the OED.

And happy thoughts like 'Mercurist', more delighted providers of news messages. A sadly obscure persumable synonym for blogger.

Yet now... to commerce: Or to the point. I forget. The darling boy is above and below, though, care of my holiday in the British Museum. Wanna see some Justinian coins? (Damn, hope that is the correct adjective? Constantinopolitan!)