A067321 One-half of odd-indexed members of A067297.

1, 32, 3072, 429760, 71386880, 13057591296, 2539643772928, 515384111218688, 107895796673347584, 23131454701441122304, 5052953723661587578880, 1120663604347562971103232, 251676943773831910414876672

Offset: 0

Author

Wolfdieter Lang, Feb 05 2002

Keywords

• nonn
• easy

Crossrefs

Cf. A067320 (even-indexed members of A067297).

Formula

a(n) = A067297(2n+1)/2.

G.f.: A(x) = (f(y) - f(-y))/y with f(y) := (-1 + 9*y + (1+6*y)*c(y))/((1-y)*(1+5*y)*c(y) - 1 + 11*y - y^2) where c(y) is g.f. of A000108 (Catalan) and y=4*sqrt(x).