A111866 Divide n! repeatedly by i! for i from floor(n/2) down through 2; a(n) = remaining quotient.

1, 1, 2, 6, 3, 15, 5, 35, 35, 105, 7, 77, 77, 1001, 143, 429, 2145, 36465, 12155, 230945, 46189, 323323, 29393, 676039, 676039, 16900975, 1300075, 2340135, 334305, 9694845, 215441, 6678671, 100180065, 3305942145, 64822395, 2268783825

Offset: 0

Author

Jon Perry, Nov 23 2005

Keywords

• nonn

Examples

			a(9): 9!/(4!*4!*3!) = 105.
		

Crossrefs

Cf. A055773.

Programs

Mathematica

f[n_] := Block[{k = Floor[n/2], m = n!}, While[k > 1, While[ Mod[m, k! ] == 0, m /= k! ]; k-- ]; m]; Table[ f[n], {n, 0, 35}] (* Robert G. Wilson v *)

PARI

a(n)=c=n!;forstep(d=floor(n/2),2,-1, while (c%(d!)==0,c/=d!));c

Extensions

More terms from Robert G. Wilson v, Nov 25 2005