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,-199,495).
FORMULA
a(n) = 25*5^n/24 -81*9^n/8 +121*11^n/12. - R. J. Mathar, Jun 30 2013
a(0)=1, a(1)=25, a(2)=426; for n>2, a(n) = 25*a(n-1) -199*a(n-2) +495*a(n-3). - Vincenzo Librandi, Jul 03 2013
a(n) = 20*a(n-1) -99*a(n-2) +5^n. - Vincenzo Librandi, Jul 03 2013
MATHEMATICA
CoefficientList[Series[1 / ((1 - 5 x) (1 - 9 x) (1 - 11 x)), {x, 0, 20}], x] (* Vincenzo Librandi, Jul 03 2013 *)
LinearRecurrence[{25, -199, 495}, {1, 25, 426}, 20] (* Harvey P. Dale, Feb 27 2023 *)
PROG
(Magma) m:=20; R<x>:=PowerSeriesRing(Integers(), m); Coefficients(R!(1/((1-5*x)*(1-9*x)*(1-11*x)))); /* or */ I:=[1, 25, 426]; [n le 3 select I[n] else 25*Self(n-1)-199*Self(n-2)+495*Self(n-3): n in [1..20]]; // Vincenzo Librandi, Jul 03 2013
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
STATUS
approved