OFFSET
0,2
FORMULA
a(n) = 1/2*sum(k=0..(n-1)/2,(4^(n-2*k)*sum(i=0..2*k+1, (i-2*k-1)^(2*n)*binomial(4*k+2,i)*(-1)^(n-i+k-1)))/(2*k+1)!). - Vladimir Kruchinin, Jun 28 2011
MATHEMATICA
With[{nn=30}, Take[CoefficientList[Series[Sin[Sin[x]^2] , {x, 0, nn}], x] Range[ 0, nn]!, {1, -1, 2}]] (* Harvey P. Dale, Feb 19 2020 *)
PROG
(Maxima)
a(n):=1/2*sum((4^(n-2*k)*sum((i-2*k-1)^(2*n)*binomial(4*k+2, i)*(-1)^(n-i+k-1), i, 0, 2*k+1))/(2*k+1)!, k, 0, (n-1)/2); /* Vladimir Kruchinin, Jun 28 2011 */
CROSSREFS
KEYWORD
sign
AUTHOR
EXTENSIONS
Extended with signs by Olivier Gérard, Mar 15 1997
Edited by N. J. A. Sloane, May 31 2008 at the suggestion of R. J. Mathar
Prior Mathematica program replaced by Harvey P. Dale, Feb 19 2020
STATUS
approved