OFFSET
0,2
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..100
FORMULA
a(n)=sum(m=0..(n-1)/2, sum(j=4*m+2..2*n, binomial(j-1,4*m+1)*(j)!*2^(2*n-j)*(-1)^(n+m+j+1)*stirling2(2*n,j))/(2*m+1)!). - Vladimir Kruchinin, Jun 10 2011
EXAMPLE
sin(tan(x)*tan(x))=2/2!*x^2+16/4!*x^4+152/6!*x^6-5504/8!*x^8...
MATHEMATICA
With[{nn=30}, Take[CoefficientList[Series[Sin[Tan[x]^2], {x, 0, nn}], x] Range[0, nn]!, {1, -1, 2}]] (* Harvey P. Dale, May 17 2012 *)
PROG
(Maxima)
a(n):=sum(sum(binomial(j-1, 4*m+1)*(j)!*2^(2*n-j)*(-1)^(n+m+j+1)*stirling2(2*n, j), j, 4*m+2, 2*n)/(2*m+1)!, m, 0, (n-1)/2); /* Vladimir Kruchinin, Jun 10 2011 */
CROSSREFS
KEYWORD
sign
AUTHOR
EXTENSIONS
Extended with signs by Olivier Gérard, Mar 15 1997
STATUS
approved