OFFSET
0,2
LINKS
Seiichi Manyama, Table of n, a(n) for n = 0..313
FORMULA
a(n) = (-1)^n * A144505(2*n+1, n).
a(n) ~ 3^(3*n + 1/2) * n^(n - 1/2) / (sqrt(Pi) * 2^(n + 1/2) * exp(n - 2/3)). - Vaclav Kotesovec, Apr 06 2019
MATHEMATICA
Table[Sum[(2*n + k)!/((n - k)!*k!*2^k)/n!, {k, 0, n}], {n, 0, 20}] (* Vaclav Kotesovec, Apr 06 2019 *)
PROG
(PARI) {a(n) = sum(k=0, n, (2*n+k)!/((n-k)!*k!*2^k))/n!}
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Apr 06 2019
STATUS
approved