A182370 - OEIS

%I #13 Apr 26 2012 19:10:20

%S 1,1,20,3246670537110000

%N a(n) = (n!)!/(n!^(n-1)!).

%C n^(n-1)! divides (n!)! because the product (n!)! = 1*2*3*...*n*(n+1)*...*n! contains (n-1)! divisors such that n, 2n, 3n,...,(n-1)!*n = n!

%C a(5) contains 149 digits; a(6) contains 1404 decimal digits; a(7) contains 13808 decimal digits; a(8) contains 144975 decimal digits.

%p for n from 1 to 5 do: x:= (n!)!/(n!^(n-1)!): printf(`%d, `,k):od:

%Y Cf. A000142.

%K nonn

%O 1,3

%A _Michel Lagneau_, Apr 26 2012