A309294 (1/2) times the sum of the elements of all subsets of [n] whose sum is divisible by two.

0, 0, 1, 6, 20, 60, 168, 448, 1152, 2880, 7040, 16896, 39936, 93184, 215040, 491520, 1114112, 2506752, 5603328, 12451840, 27525120, 60555264, 132644864, 289406976, 629145600, 1363148800, 2944401408, 6341787648, 13623099392, 29192355840, 62411243520

Offset

0,4

Links

Alois P. Heinz, Table of n, a(n) for n = 0..1000

Index entries for linear recurrences with constant coefficients, signature (6,-12,8).

Formula

G.f.: -x^2*(4*x^3-4*x^2+1)/(2*x-1)^3.

a(n) = 6*a(n-1) - 12*a(n-2) + 8*a(n-3). - Wesley Ivan Hurt, Jun 05 2026

Mathematica

LinearRecurrence[{6, -12, 8}, {0, 0, 1, 6, 20, 60}, 40] (* Harvey P. Dale, Aug 27 2021 *)

Crossrefs

Column k=2 of A309280.

Sequence in context: A212689 A027984 A342313 * A018808 A027107 A247307

Adjacent sequences: A309291 A309292 A309293 * A309295 A309296 A309297

Keyword

nonn,easy

Author

Alois P. Heinz, Jul 21 2019

Status

approved