OFFSET
0,2
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..200
Index entries for linear recurrences with constant coefficients, signature (21,-133,267,-154).
FORMULA
a(n)=(11^(n+3) - 3*7^(n+3) + 8*2^(n+3) - 6)/360. [Yahia Kahloune, Jun 30 2013]
a(0)=1, a(1)=21, a(2)=308, a(3)=3942; for n>3, a(n) = 21*a(n-1) -133*a(n-2) +267*a(n-3) -154*a(n-4). - Vincenzo Librandi, Jul 08 2013
a(0)=1, a(1)=21; for n>1, a(n) = 18*a(n-1) -77*a(n-2) +2^n -1. - Vincenzo Librandi, Jul 08 2013
MATHEMATICA
CoefficientList[Series[1 / ((1 - x) (1 - 2 x) (1 - 7 x) (1 - 11 x)), {x, 0, 20}], x] (* Vincenzo Librandi, Jul 08 2013 *)
LinearRecurrence[{21, -133, 267, -154}, {1, 21, 308, 3942}, 20] (* Harvey P. Dale, May 31 2020 *)
PROG
(Magma) I:=[1, 21, 308, 3942]; [n le 4 select I[n] else 21*Self(n-1)-133*Self(n-2)+267*Self(n-3)-154*Self(n-4): n in [1..25]]; /* or */ m:=25; R<x>:=PowerSeriesRing(Integers(), m); Coefficients(R!(1/((1-x)*(1-2*x)*(1-7*x)*(1-11*x)))); // Vincenzo Librandi, Jul 08 2013
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
STATUS
approved