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A009257 E.g.f. exp(tanh(log(1+x))). 0
1, 1, 0, -2, 4, 6, -74, 190, 1128, -14336, 51616, 404856, -7330520, 41023048, 250083744, -7532037344, 65189204416, 185746926720, -13324842809792, 175157684686144, -215786634724224, -35458746254274944, 711274631768613760 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,4

LINKS

Table of n, a(n) for n=0..22.

FORMULA

a(n)=sum(m=1..n, sum(r=0..n-m, stirling1(n,r+m)*sum(k=0..r, binomial(k+m-1,m-1)*(k+m)!*(-1)^(k)*2^(r-k)*stirling2(r+m,k+m)))/m!), n>0, a(0)=1. [From Vladimir Kruchinin, Jun 06 2011]

MATHEMATICA

With[{nn=30}, CoefficientList[Series[Exp[Tanh[Log[1+x]]], {x, 0, nn}], x] Range[0, nn]!] (* Harvey P. Dale, Jan 15 2015 *)

PROG

(Maxima)

a(n):=sum(sum(stirling1(n, r+m)*sum(binomial(k+m-1, m-1)*(k+m)!*(-1)^(k)*2^(r-k)*stirling2(r+m, k+m), k, 0, r), r, 0, n-m)/m!, m, 1, n); /* Vladimir Kruchinin, Jun 06 2011 */

CROSSREFS

Sequence in context: A333456 A348244 A066220 * A098757 A335709 A056012

Adjacent sequences:  A009254 A009255 A009256 * A009258 A009259 A009260

KEYWORD

sign,easy

AUTHOR

R. H. Hardin

EXTENSIONS

Extended with signs by Olivier Gérard, Mar 15 1997

Prior Mathematica program replaced by Harvey P. Dale, Jan 15 2015

STATUS

approved

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Last modified October 26 13:09 EDT 2021. Contains 348267 sequences. (Running on oeis4.)