A130844 a(n) = 2*a(n-1) + a(n-2) - a(n-3) + a(n-4), with a(1) = 0, a(2) = 3, a(3) = 5 and a(4) = 17.

0, 3, 5, 17, 36, 87, 198, 464, 1075, 2503, 5815, 13522, 31431, 73072, 169868, 394899, 918025, 2134153, 4961300, 11533627, 26812426, 62331332, 144902763, 336858059, 783099975, 1820486578, 4232117835, 9838480332, 22871691896, 53170232867

Offset

1,2

Links

Table of n, a(n) for n=1..30.

Index entries for linear recurrences with constant coefficients, signature (2,1,-1,1).

Formula

G.f.: x^2*(3 - x + 4*x^2)/((1 + x)*(1 - 3*x + 2*x^2 - x^3)). - Colin Barker, Nov 02 2012

Mathematica

LinearRecurrence[{2, 1, -1, 1}, {0, 3, 5, 17}, 30] (* Harvey P. Dale, Dec 20 2014 *)

Prog

(PARI) m=30; v=concat([0, 3, 5, 17], vector(m-4)); for(n=5, m, v[n] = 2*v[n-1] +v[n-2] -v[n-3] +v[n-4]); v \\ G. C. Greubel, Nov 03 2018
(Magma) I:=[0, 3, 5, 17]; [n le 4 select I[n] else 2*Self(n-1) +Self(n-2) -Self(n-3) + Self(n-4): n in [1..30]]; // G. C. Greubel, Nov 03 2018

Crossrefs

Cf. A107479, A107480, A109538, A109543, A109544, A114749, A125950, A143335, A147851.

Sequence in context: A148509 A148510 A215396 * A148511 A148512 A148513

Adjacent sequences: A130841 A130842 A130843 * A130845 A130846 A130847

Keyword

nonn,easy

Author

Roger L. Bagula, Jul 20 2007

Extensions

New name (after Colin Barker) by Franck Maminirina Ramaharo, Nov 02 2018

Edited by N. J. A. Sloane, Nov 03 2018

Status

approved