OFFSET
0,2
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..200
Index entries for linear recurrences with constant coefficients, signature (25,-203,575,-396).
FORMULA
a(n) = (12*11^(n+3) - 21*9^(n+3) + 4^(n+5) - 7)/1680. - Yahia Kahloune, Jun 26 2013
a(0)=1, a(1)=25, a(2)=422, a(3)=6050; for n>3, a(n) = 25*a(n-1) -203*a(n-2) +575*a(n-3) -396*a(n-4). - Vincenzo Librandi, Jul 11 2013
a(0)=1, a(1)=25; for n>1, a(n) = 20*a(n-1) -99*a(n-2) +(4^n - 1)/3. - Vincenzo Librandi, Jul 11 2013
MATHEMATICA
CoefficientList[Series[1 / ((1 - x) (1 - 4 x) (1 - 9 x) (1 - 11 x)), {x, 0, 20}], x] (* Vincenzo Librandi, Jul 11 2013 *)
LinearRecurrence[{25, -203, 575, -396}, {1, 25, 422, 6050}, 20] (* Harvey P. Dale, Aug 24 2021 *)
PROG
(Magma) m:=25; R<x>:=PowerSeriesRing(Integers(), m); Coefficients(R!(1/((1-x)*(1-4*x)*(1-9*x)*(1-11*x)))); /* or */ I:=[1, 25, 422, 6050]; [n le 4 select I[n] else 25*Self(n-1)-203*Self(n-2)+575*Self(n-3)-396*Self(n-4): n in [1..25]]; // Vincenzo Librandi, Jul 11 2013
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
STATUS
approved