A027831 Expansion of 1/(1 - 4*x + 2*x^2 + 4*x^3 - 2*x^4).

1, 4, 14, 44, 134, 400, 1184, 3488, 10252, 30096, 88296, 258960, 759368, 2226560, 6528256, 19140352, 56117392, 164528960, 482376160, 1414257856, 4146398048, 12156629760, 35641443840, 104495439360

Offset

0,2

Links

Vincenzo Librandi, Table of n, a(n) for n = 0..1000

Index entries for linear recurrences with constant coefficients, signature (4,-2,-4,2)

Formula

a(n) = 4*a(n-1) - 2*a(n-2) - 4*a(n-3) + 2*a(n-4). - Vincenzo Librandi, Jun 20 2012

Mathematica

LinearRecurrence[{4, -2, -4, 2}, {1, 4, 14, 44}, 40] (* Vincenzo Librandi, Jun 20 2012 *)

Prog

(Magma) I:=[1, 4, 14, 44]; [n le 4 select I[n] else 4*Self(n-1)-2*Self(n-2)-4*Self(n-3)+2*Self(n-4): n in [1..40]]; // Vincenzo Librandi, Jun 20 2012

Crossrefs

Sequence in context: A094309 A000300 A005323 * A097894 A065835 A198643

Adjacent sequences: A027828 A027829 A027830 * A027832 A027833 A027834

Keyword

nonn,easy

Author

N. J. A. Sloane

Status

approved