A140659 a(n) = floor(A140657(n+2)/10).

0, 0, 1, 2, 6, 12, 25, 50, 102, 204, 409, 818, 1638, 3276, 6553, 13106, 26214, 52428, 104857, 209714, 419430, 838860, 1677721, 3355442, 6710886, 13421772, 26843545, 53687090, 107374182, 214748364, 429496729, 858993458, 1717986918, 3435973836

Offset: 0

Author

Paul Curtz, Jul 10 2008

Keywords

• nonn

Links

• Michel Marcus, Table of n, a(n) for n = 0..100

Crossrefs

Cf. A093387.

Programs

Mathematica

a[ n_] := If[n < 2, 0, 2 a[n - 1] + If[ EvenQ[n], Mod[n/2, 2, 1], 0]]; (* Michael Somos, Mar 02 2014 *)

PARI

f(n) = 2^n+3*(-1)^n; \\ A140657
a(n) = f(n+2)\10; \\ Michel Marcus, Sep 08 2019

Formula

a(2n+2) = 4*a(2n)+A000034(n).

a(2n+1) = 2*a(2n).

Extensions

Edited and extended by R. J. Mathar, Jul 29 2008

Name corrected by Michel Marcus, Sep 08 2019