OFFSET
1,1
LINKS
FORMULA
a(n) = Sum_{k=0}^{n-1} binomial(n -1,k) (-2)^k (2n - k)!.
Conjecture: D-finite with recurrence (-n+1)*a(n) +2*(2*n-1)*(n^2-n-1)*a(n-1) +4*n^2*(n-2)*a(n-2)=0. - R. J. Mathar, Jan 27 2022
MATHEMATICA
f[n_] := Sum[(-2)^k (2 n - k)! Binomial[n - 1, k], {k, 0, n - 1}]; Array[f, 13] (* Robert G. Wilson v, Oct 16 2010 *)
PROG
(Other) SAS datastep: data _null_; do n = 1 to 7; a = 0; do _n_ = 0 to n-1; a = a + (-2)**_n_ * comb(n-1, _n_)*fact(2*n-_n_); end; output; put "a(" n ")=" a; end; run;
CROSSREFS
KEYWORD
nonn
AUTHOR
Arin Chaudhuri (arin.chaudhuri(AT)gmail.com), Oct 06 2010
EXTENSIONS
a(8) and onward from Robert G. Wilson v, Oct 16 2010
STATUS
approved