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

0,4

Links

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

Formula

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

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

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 *)

Prog

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

Crossrefs

Cf. A093387.

Sequence in context: A116562 A045925 A128020 * A238462 A099495 A232164

Adjacent sequences: A140656 A140657 A140658 * A140660 A140661 A140662

Keyword

nonn

Author

Paul Curtz, Jul 10 2008

Extensions

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

Name corrected by Michel Marcus, Sep 08 2019

Status

approved