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

0,3

Links

Table of n, a(n) for n=0..35.

Example

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

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 *)

Prog

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

Crossrefs

Cf. A055773.

Sequence in context: A094302 A094300 A055773 * A251753 A072155 A094299

Adjacent sequences: A111863 A111864 A111865 * A111867 A111868 A111869

Keyword

nonn

Author

Jon Perry, Nov 23 2005

Extensions

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

Status

approved