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A009277 E.g.f. exp(tanh(x)^2) (even powers only). 1
1, 2, -4, -88, 4496, -155488, 675776, 903834752, -178181918464, 26154843525632, -2632795710260224, -207121926659381248, 274561534481040183296, -132684091405061956722688, 50873850498309673207709696 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

G. C. Greubel, Table of n, a(n) for n = 0..235

FORMULA

a(n) = Sum_{m=1..n} (Sum_{k=0..2*n-2*m} (binomial(k+2*m-1, 2*m-1)*(k+2*m)!*(-1)^(k)*2^(2*n-2*m-k)*stirling2(2*n, k+2*m))/m!). - Vladimir Kruchinin, Jun 06 2011

MATHEMATICA

Exp[ Tanh[ x ]^2 ] (* Even Part *)

PROG

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

(PARI) x = 'x + O(x^50); select(x->x, Vec(serlaplace(exp(tanh(x)^2)))) \\ Michel Marcus, Apr 01 2017

CROSSREFS

Sequence in context: A015170 A013146 A116310 * A018410 A270484 A327427

Adjacent sequences:  A009274 A009275 A009276 * A009278 A009279 A009280

KEYWORD

sign

AUTHOR

R. H. Hardin

EXTENSIONS

Extended with signs by Olivier Gérard, Mar 15 1997

STATUS

approved

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Last modified June 17 14:21 EDT 2021. Contains 345083 sequences. (Running on oeis4.)