A019496 a(n) = 3*a(n-1) - 3*a(n-3) + 2*a(n-4), with a(0)=4, a(1)=11.

4, 11, 30, 81, 218, 586, 1575, 4233, 11377, 30578, 82185, 220890, 593690, 1595671, 4288713, 11526849, 30980914, 83267945, 223800714, 601513098, 1616697287, 4345225609, 11678738961, 31389151218, 84365171401

Offset

0,1

References

R. K. Guy, personal communication.

Links

G. C. Greubel, Table of n, a(n) for n = 0..1000

Index entries for linear recurrences with constant coefficients, signature (3, 0, -3, 2).

Formula

G.f.: (4-x-3*x^2+3*x^3)/(1-3*x+3*x^3-2*x^4). - Harvey P. Dale, Oct 25 2011

Mathematica

LinearRecurrence[{3, 0, -3, 2}, {4, 11, 30, 81}, 30] (* Harvey P. Dale, Oct 25 2011 *)

Prog

(PARI) my(x='x+O('x^30)); Vec((4-x-3*x^2+3*x^3)/(1-3*x+3*x^3-2*x^4)) \\ G. C. Greubel, Mar 24 2019
(Magma) I:=[4, 11, 30, 81]; [n le 4 select I[n] else 3*Self(n-1)- 3*Self(n-3) +2*Self(n-4): n in [1..30]]; // G. C. Greubel, Mar 24 2019
(Sage) ((4-x-3*x^2+3*x^3)/(1-3*x+3*x^3-2*x^4)).series(x, 30).coefficients(x, sparse=False) # G. C. Greubel, Mar 24 2019

Crossrefs

Sequence in context: A128098 A341104 A019495 * A021006 A078141 A090327

Adjacent sequences: A019493 A019494 A019495 * A019497 A019498 A019499

Keyword

nonn

Author

N. J. A. Sloane

Status

approved