A240526 a(n) = 2^(n-2)*(2^(n+4)-(-1)^n+13).

7, 23, 76, 284, 1072, 4208, 16576, 65984, 262912, 1050368, 4197376, 16784384, 67121152, 268464128, 1073790976, 4295081984, 17180065792, 68719935488, 274878693376, 1099513462784, 4398049656832, 17592193384448, 70368756760576, 281475006070784, 1125899957174272

Offset

0,1

Links

Vincenzo Librandi, Table of n, a(n) for n = 0..200

Index entries for linear recurrences with constant coefficients, signature (4,4,-16).

Formula

G.f.: (7-5*x-44*x^2)/(1-4*x-4*x^2+16*x^3).

a(n) = 4*a(n-1)+4*a(n-2)-16*a(n-3) for n>2.

Maple

A240526:=n->2^(n-2)*(2^(n+4)-(-1)^n+13); seq(A240526(n), n=0..30); # Wesley Ivan Hurt, Apr 10 2014

Mathematica

CoefficientList[Series[(7 - 5 x - 44 x^2)/(1 - 4 x - 4 x^2 + 16 x^3), {x, 0, 30}], x]

Prog

(Magma) [2^(n-2)*(2^(n+4)-(-1)^n+13): n in [0..25]] /* or */ I:=[7, 23, 76]; [n le 3 select I[n] else 4*Self(n-1)+4*Self(n-2)-16*Self(n-3): n in [1..30]];
(PARI) a(n)=(2^(n+4)-(-1)^n+13)<<(n-2) \\ Charles R Greathouse IV, Aug 26 2014

Crossrefs

Cf. A225826.

Sequence in context: A242496 A356684 A048539 * A018886 A145842 A086908

Adjacent sequences: A240523 A240524 A240525 * A240527 A240528 A240529

Keyword

nonn,easy

Author

Vincenzo Librandi, Apr 07 2014

Status

approved