A009153 Expansion of e.g.f. cosh(sinh(x)*exp(x)).

1, 0, 1, 6, 29, 140, 757, 4858, 36409, 302520, 2681769, 25018510, 245905365, 2559272196, 28264854685, 330408571202, 4065526003313, 52349977261040, 702393407898705, 9795673312888214, 141820637175889805

Offset

0,4

Links

Vincenzo Librandi, Table of n, a(n) for n = 0..100

Vaclav Kotesovec, Asymptotic solution of the equations using the Lambert W-function

Formula

a(n) = Sum_{k=0..n} Stirling2(n, k)*(1+(-1)^k)/2*2^(n-k). - Vladeta Jovovic, Sep 26 2003

G.f.: 1 + Sum_{k>=0} x^(2*k+2)/Product_{i=0..2*k+2} (1-2*i*x). - Sergei N. Gladkovskii, Jan 06 2013

G.f.: 1 + x^2/( G(0)-x^2 ) where G(k) = x^2 + (4*x*k+2*x-1)*(4*x*k+4*x-1) - x^2*(4*x*k+2*x-1)*(4*x*k+4*x-1)/G(k+1); (continued fraction). - Sergei N. Gladkovskii, Jan 06 2013

a(n) ~ cosh(exp(r)*sinh(r)) * n^(n+1/2) / (r^(n+1/2) * exp(n+r) * sqrt(exp(2*r) * r * sech(exp(r)*sinh(r))^2 + (1+2*r) * tanh(exp(r)*sinh(r)))), where r is the root of the equation r*exp(r)*(cosh(r) + sinh(r))*tanh(exp(r)*sinh(r)) = n. - Vaclav Kotesovec, Aug 06 2014

Mathematica

CoefficientList[Series[Cosh[Sinh[x]*E^x], {x, 0, 20}], x] * Range[0, 20]! (* Vaclav Kotesovec, Aug 06 2014 *)
Table[Sum[StirlingS2[n, k]*(1+(-1)^k)/2*2^(n-k), {k, 0, n}], {n, 0, 20}] (* Vaclav Kotesovec, Aug 06 2014 after Vladeta Jovovic *)
Table[(BellB[n, 1/2] + BellB[n, -1/2]) 2^(n-1), {n, 0, 20}] (* Vladimir Reshetnikov, Nov 01 2015 *)

Prog

(PARI) a(n) = sum(k=0, n, stirling(n, k, 2)*(1+(-1)^k)/2*2^(n-k)); \\ Michel Marcus, Nov 02 2015

Crossrefs

Cf. A009599, A065143.

Sequence in context: A030221 A271753 A367469 * A012325 A125785 A186651

Adjacent sequences: A009150 A009151 A009152 * A009154 A009155 A009156

Keyword

nonn,easy

Author

R. H. Hardin

Extensions

Extended and signs tested by Olivier Gérard, Mar 15 1997

Status

approved