OFFSET
0,1
FORMULA
a(n) = 2^(4*n + 1)*Gamma(n + 1)^2.
a(n) = a(n-1)*(4*n)^2 for n > 0.
MAPLE
a := proc(n) option remember; if n = 0 then 2 else 16*a(n-1)*n^2 fi end:
seq(a(n), n = 0..13);
PROG
(PARI) \p100; binom(n, k)=gamma(n+1)/(gamma(k+1)*gamma(n-k+1));
for(n=0, 14, print1(round((Pi/2)*(2*n+1)!*binom(2*n+1, (2*n+1)/2)), ", ")) \\ Hugo Pfoertner, Dec 05 2019
CROSSREFS
KEYWORD
nonn
AUTHOR
Peter Luschny, Dec 05 2019
STATUS
approved