A021634 - OEIS

%I #12 Sep 28 2023 09:51:23

%S 1,21,298,3594,39763,417567,4236796,41963988,408348325,3920543913,

%T 37248255694,350941450782,3284131050487,30562445793459,

%U 283104150028192,2612274474873576,24025167335391049,220344082704460605

%N Expansion of 1/((1-x)(1-3x)(1-8x)(1-9x)).

%H Vincenzo Librandi, <a href="/A021634/b021634.txt">Table of n, a(n) for n = 0..200</a>

%H <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (21, -143, 339, -216).

%F a(n) = (35*9^(n+3) - 48*8^(n+3) + 28*3^(n+3) - 15)/1680. [_Yahia Kahloune_, Aug 12 2013]

%t CoefficientList[Series[1 / ((1 - x) (1 - 3 x) (1 - 8 x) (1 - 9 x)), {x, 0, 20}], x] (* _Vincenzo Librandi_, Jul 11 2013 *)

%K nonn,easy

%O 0,2

%A _N. J. A. Sloane_.