A263622 a(n) = (3^(n+1)-2^(n+2)+2*n+1)/4.

0, 1, 4, 14, 47, 153, 486, 1516, 4669, 14255, 43268, 130818, 394491, 1187557, 3570850, 10728920, 32219513, 96724059, 290303232, 871171822, 2614039735, 7843167761, 23531600414, 70598995524, 211805375157, 635432902663, 1906332262396, 5719063896026, 17157325905779, 51472246152765

Offset

0,3

Links

Colin Barker, Table of n, a(n) for n = 0..1000

H. Gupta, On a problem in parity, Indian J. Math., 11 (1969), 157-163. [Annotated scanned copy] See Q(w) on first page.

Index entries for linear recurrences with constant coefficients, signature (7,-17,17,-6).

Formula

From Colin Barker, Oct 26 2015: (Start)

a(n) = 7*a(n-1)-17*a(n-2)+17*a(n-3)-6*a(n-4) for n>3.

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

(End)

Prog

(PARI) a(n) = (3^(n+1)-2^(n+2)+2*n+1)/4 \\ Colin Barker, Oct 26 2015
(PARI) concat(0, Vec(x*(3*x^2-3*x+1)/((x-1)^2*(2*x-1)*(3*x-1)) + O(x^40))) \\ Colin Barker, Oct 26 2015

Crossrefs

Sequence in context: A046718 A291385 A192877 * A104487 A247210 A094789

Adjacent sequences: A263619 A263620 A263621 * A263623 A263624 A263625

Keyword

nonn,easy

Author

N. J. A. Sloane, Oct 23 2015

Extensions

Typo in last term fixed by Colin Barker, Oct 26 2015

Status

approved