OFFSET
0,3
FORMULA
a(n) = numerator(4^(-n-floor(n/2))*binomial(2*n,n)*n!/floor(n/2)!^2).
MAPLE
seq(numer(4^(-n-floor(n/2))*binomial(2*n, n)*n!/iquo(n, 2)!^2), n=0..23);
MATHEMATICA
a[n_] := Numerator[Hypergeometric2F1[-n, 1/2, 1, 1] Hypergeometric2F1[-Floor[n/2], (-1)^n/2, 1, 1]]; Table[a[n], {n, 0, 22}]
PROG
(PARI) a(n) = numerator(4^(-n-floor(n/2))*binomial(2*n, n)*n!/floor(n/2)!^2); \\ Michel Marcus, Feb 15 2018
CROSSREFS
KEYWORD
nonn,frac
AUTHOR
Peter Luschny, Feb 14 2018
STATUS
approved