A319924 a(n) = A143565(2n,n) for n > 0, a(0) = 1.

1, 3, 13, 61, 281, 1261, 5545, 24025, 102961, 437581, 1847561, 7759753, 32449873, 135207801, 561632401, 2326762801, 9617286241, 39671305741, 163352435401, 671560012201, 2756930576401, 11303415363241, 46290177201841, 189368906734801, 773942488394401

Offset: 0

Author

Alois P. Heinz, Oct 01 2018

Keywords

• nonn

Links

• Alois P. Heinz, Table of n, a(n) for n = 0..1658

Crossrefs

Cf. A002457, A143565.

Programs

Maple

a:= proc(n) option remember; `if`(n<2, 2*n+1,
      ((15*n^2-29*n+10)*a(n-1)-(6*n-2)*(2*n-3)*
       a(n-2))/((n-1)*(3*n-4)))
    end:
seq(a(n), n=0..30);

Formula

a(n) = A143565(2n,n) for n > 0, a(0) = 1.

a(n) = 1 + 2 * A002457(n-1) = 1 + 2 * (2*n-1)!/(n-1)!^2 for n > 0, a(0) = 1.