A191636 a(n) = floor((-1 + 4^n)/(-1 + 2*n)).

3, 5, 12, 36, 113, 372, 1260, 4369, 15420, 55188, 199728, 729444, 2684354, 9942053, 37025580, 138547332, 520602096, 1963413621, 7429132620, 28192605840, 107269427100, 409120605684, 1563749870614, 5988829291716, 22977549119237, 88305875046480, 339894311499660

Offset: 1

Author

Clark Kimberling, Jun 09 2011

Keywords

• nonn

Links

• Vincenzo Librandi, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A191637.

Programs

Magma

[Floor((-1+4^n)/(-1+2*n)): n in [1..30] ];// Vincenzo Librandi, Sep 10 2011

Mathematica

f[n_] := Floor[(-1+4^n)/(-1+2 n)]
Table[f[n], {n, 1, 40}]     (* A191636 *)

Maxima

A191636(n):=floor((-1+4^n)/(-1+2*n))$ makelist(A191636(n),n,1,30); /* Martin Ettl, Oct 25 2012 */