A021204 Expansion of 1/((1-x)(1-2x)(1-6x)(1-11x)).

1, 20, 281, 3472, 40509, 459564, 5139121, 57034088, 630398021, 6952517572, 76586531385, 843104877888, 9278071860877, 102082299710684, 1123046352296513, 12354356208201112, 135902996287980117, 1494963427154650740, 16444780506622899145, 180893682420383385200

Offset

0,2

Links

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

Index entries for linear recurrences with constant coefficients, signature (20,-119,232,-132).

Formula

a(n) = (2*11^(n+3)-9*6^(n+3)+25*2^(n+3)-18)/900. - Yahia Kahloune, May 21 2013

a(0)=1, a(1)=20; for n>1, a(n) = 17*a(n-1) -66*a(n-2) +2^n -1. - Vincenzo Librandi, Jul 08 2013

a(0)=1, a(1)=20, a(2)=281, a(3)=3472; for n>3, a(n) = 20*a(n-1) -119*a(n-2) +232*a(n-3) -132*a(n-4). - Vincenzo Librandi, Jul 08 2013

Mathematica

CoefficientList[Series[1 / ((1 - x) (1 - 2 x) (1 - 6 x) (1 - 11 x)), {x, 0, 30}], x]  (* Harvey P. Dale, Mar 12 2011 *)

Prog

(PARI) x='x+O('x^66); Vec(1/((1-x)*(1-2*x)*(1-6*x)*(1-11*x))) \\ Joerg Arndt, May 21 2013
(Magma) I:=[1, 20, 281, 3472]; [n le 4 select I[n] else 20*Self(n-1)-119*Self(n-2)+232*Self(n-3)-132*Self(n-4): n in [1..25]]; // Vincenzo Librandi, Jul 08 2013
(Magma) m:=25; R<x>:=PowerSeriesRing(Integers(), m); Coefficients(R!(1/((1-x)*(1-2*x)*(1-6*x)*(1-11*x)))); // Vincenzo Librandi, Jul 08 2013

Crossrefs

Sequence in context: A028294 A278360 A019040 * A017953 A016317 A021404

Adjacent sequences: A021201 A021202 A021203 * A021205 A021206 A021207

Keyword

nonn,easy

Author

N. J. A. Sloane

Status

approved