A016262 Expansion of 1/((1-x)(1-9x)(1-11x)).

1, 21, 322, 4362, 55363, 675423, 8027524, 93683604, 1078947205, 12304267305, 139269572806, 1567268992926, 17557692150727, 195994212714867, 2181672731375368, 24230027568735528, 268614950968549129, 2973526290066165309, 32877645655436942410, 363173810392188482610

Offset

0,2

Links

Table of n, a(n) for n=0..19.

Index entries for linear recurrences with constant coefficients, signature (21,-119,99).

Formula

a(n) = (4*11^(n+2)-5*9^(n+2)+1)/80. - Bruno Berselli, Mar 21 2011

a(n) = 20*a(n-1)-99*a(n-2)+1, n>=2. - Vincenzo Librandi, Mar 21 2011

a(n) = 21*a(n-1)-119*a(n-2)+99*a(n-3). - Wesley Ivan Hurt, Mar 27 2015

Maple

a:=n->sum((11^(n-j)-9^(n-j))/2, j=0..n): seq(a(n), n=1..17); # Zerinvary Lajos, Jan 12 2007

Mathematica

CoefficientList[Series[1/((1 - x) (1 - 9 x) (1 - 11 x)), {x, 0, 20}], x] (* Wesley Ivan Hurt, Mar 27 2015 *)
LinearRecurrence[{21, -119, 99}, {1, 21, 322}, 20] (* Harvey P. Dale, Jun 07 2022 *)

Prog

(Magma) [(4*11^(n+2)-5*9^(n+2)+1)/80 : n in [0..20]]; // Wesley Ivan Hurt, Mar 27 2015

Crossrefs

Sequence in context: A036737 A141267 A346321 * A001233 A145148 A214099

Adjacent sequences: A016259 A016260 A016261 * A016263 A016264 A016265

Keyword

nonn,easy

Author

N. J. A. Sloane

Status

approved