OFFSET
0,1
LINKS
Seiichi Manyama, Table of n, a(n) for n = 0..402
FORMULA
n^2*a(n) = (2*n+1)*(n^2+n+1)*a(n-1) + (n+1)^2*a(n-2). - Seiichi Manyama, Apr 07 2019
MAPLE
f2:=proc(n) local k; add((n+k+2)!/((n-k)!*k!*2^k), k=0..n); end; [seq(f2(n), n=0..50)];
PROG
(PARI) {a(n) = sum(k=0, n, (n+k+2)!/((n-k)!*k!*2^k))} \\ Seiichi Manyama, Apr 07 2019
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Dec 16 2008
STATUS
approved