

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*n2*m} (binomial(k+2*m1, 2*m1)*(k+2*m)!*(1)^(k)*2^(2*n2*mk)*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*m1, 2*m1)*(k+2*m)!*(1)^(k)*2^(2*n2*mk)*stirling2(2*n, k+2*m), k, 0, 2*n2*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



