login
A016262
Expansion of 1/((1-x)(1-9x)(1-11x)).
0
1, 21, 322, 4362, 55363, 675423, 8027524, 93683604, 1078947205, 12304267305, 139269572806, 1567268992926, 17557692150727, 195994212714867, 2181672731375368, 24230027568735528, 268614950968549129, 2973526290066165309, 32877645655436942410, 363173810392188482610
OFFSET
0,2
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
KEYWORD
nonn,easy
STATUS
approved