A009777 - OEIS

A009777

E.g.f. tanh(log(1+x))*cosh(x).

0, 1, -1, 3, 0, -25, 165, -623, 392, 18909, -206685, 1233551, -1161336, -81119597, 1241356025, -10102782675, 12681799920, 1158387845177, -22791296600793, 234950313889819, -368659923645520, -41597707520306049

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OFFSET

0,4

LINKS

Table of n, a(n) for n=0..21.

FORMULA

a(n)=(sum(i=0..(n-1)/2, binomial(n,2*i)*(sum(m=1..n-2*i, (sum(k=1..m, (-1)^(k+1)*k!*2^(m-k)*stirling2(m,k)))*stirling1(n-2*i,m))))). - Vladimir Kruchinin, Jun 29 2011

PROG

(Maxima)

a(n):=(sum(binomial(n, 2*i)*(sum((sum((-1)^(k+1)*k!*2^(m-k)*stirling2(m, k), k, 1, m))*stirling1(n-2*i, m), m, 1, n-2*i)), i, 0, (n-1)/2)); /* Vladimir Kruchinin, Jun 29 2011 */

CROSSREFS

Sequence in context: A344996 A057379 A360063 * A138543 A238104 A143769

Adjacent sequences: A009774 A009775 A009776 * A009778 A009779 A009780

KEYWORD

sign,easy

AUTHOR

R. H. Hardin

EXTENSIONS

Extended with signs by Olivier Gérard, Mar 15 1997

STATUS

approved