OFFSET
0,2
LINKS
G. C. Greubel, Table of n, a(n) for n = 0..250
FORMULA
a(n) = (2*n+1)*Sum_{m=1..2*n} (Sum_{i=0..m} (-1)^(i+m/2)*(m-2*i)^(2*n) *binomial(m, i))/(2^m*m!), n>0, a(0)=1. - Vladimir Kruchinin, Jun 29 2011
MATHEMATICA
With[{nn=40}, Take[CoefficientList[Series[x Cos[Sinh[x]], {x, 0, nn}], x] Range[ 0, nn-1]!, {2, -1, 2}]] (* Harvey P. Dale, May 22 2017 *)
PROG
(Maxima)
a(n):=if n=0 then 1 else (sum((sum((-1)^(i+m/2)*(m-2*i)^(2*n)*binomial(m, i), i, 0, m))/(2^m*m!), m, 1, 2*n))*(2*n+1); /* Vladimir Kruchinin, Jun 28 2011 */
(PARI) x='x+O('x^60); v=Vec(serlaplace(x*cos(sinh(x)))); vector((#v-1)\2 , n, v[2*n-1]) \\ G. C. Greubel, Jul 23 2018
CROSSREFS
KEYWORD
sign
AUTHOR
EXTENSIONS
Extended with signs by Olivier Gérard, Mar 15 1997
STATUS
approved