A117251 Column 0 of triangle A117250.

1, 1, -1, 4, -40, 896, -43008, 4325376, -899678208, 383862702080, -334114095890432, 590956713604022272, -2117988861556815822848, 15348576513041885002989568, -224527747847927003472304537600, 6621592717332784844802427579269120

Offset

0,4

Links

Table of n, a(n) for n=0..15.

Formula

a(n) = (-1)^(n-1) * C(2*n,n)/(2*n-1) * 2^((n-1)*(n-2)/2-1).

Prog

(PARI) a(n)=(-1)^(n-1)*2^((n-1)*(n-2)/2-1)*binomial(2*n, n)/(2*n-1)

Crossrefs

Sequence in context: A121276 A013053 A055128 * A220404 A211040 A012957

Adjacent sequences: A117248 A117249 A117250 * A117252 A117253 A117254

Keyword

sign

Author

Paul D. Hanna, Mar 14 2006

Status

approved