OFFSET
0,2
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..200
Index entries for linear recurrences with constant coefficients, signature (18,-104,222,-135).
FORMULA
a(0)=1, a(1)=18, a(2)=220, a(3)=2310, a(n)=18*a(n-1)- 104*a(n-2)+ 222*a(n-3)- 135*a(n-4). - Harvey P. Dale, Nov 05 2011
a(n) = (3*9^(n+2) - 2*5^(n+3) + 8*3^(n+2) - 1)/64. - Yahia Kahloune, Jun 26 2013
a(0)=1, a(1)=18; for n>1, a(n) = 14*a(n-1) -45*a(n-2) +(3^n-1)/2. - Vincenzo Librandi, Jul 10 2013
MATHEMATICA
CoefficientList[Series[1/((1-x)(1-3x)(1-5x)(1-9x)), {x, 0, 20}], x] (* or *) LinearRecurrence[{18, -104, 222, -135}, {1, 18, 220, 2310}, 20] (* Harvey P. Dale, Nov 05 2011 *)
PROG
(Magma) m:=25; R<x>:=PowerSeriesRing(Integers(), m); Coefficients(R!(1/((1-x)*(1-3*x)*(1-5*x)*(1-9*x)))); // Vincenzo Librandi, Jul 10 2013
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
STATUS
approved