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 A295871 a(n) = numerator(hypergeom([-n, 1/2], [1], 1)*hypergeom([-floor(n/2), (-1)^n/2], [1], 1)). 0
 1, 1, 3, 15, 105, 945, 1155, 15015, 225225, 3828825, 2909907, 61108047, 156165009, 3904125225, 2151252675, 62386327575, 1933976154825, 63821213109225, 27577067392875, 1020351493536375, 1591748329916745, 65261681526586545, 23192167815233235, 1043647551685495575 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 LINKS 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 Cf. A295864. Sequence in context: A189919 A251598 A338725 * A293997 A328866 A247304 Adjacent sequences:  A295868 A295869 A295870 * A295872 A295873 A295874 KEYWORD nonn,frac AUTHOR Peter Luschny, Feb 14 2018 STATUS approved

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Last modified July 25 13:05 EDT 2021. Contains 346290 sequences. (Running on oeis4.)