OFFSET
0,2
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..200
Index entries for linear recurrences with constant coefficients, signature (15,-62,72).
FORMULA
a(n) = (2/7)*2^n - (8/5)*4^n + (81/35)*9^n. - Antonio Alberto Olivares, May 12 2012
a(n) = 15*a(n-1) - 62*a(n-2) + 72*a(n-3). - Vincenzo Librandi, Jun 26 2013
MATHEMATICA
CoefficientList[Series[1 / ((1 - 2 x) (1 - 4 x) (1 - 9 x)), {x, 0, 20}], x] (* Vincenzo Librandi, Jun 26 2013 *)
LinearRecurrence[{15, -62, 72}, {1, 15, 163}, 30] (* Harvey P. Dale, Dec 03 2018 *)
PROG
(PARI) Vec(1/((1-2*x)*(1-4*x)*(1-9*x))+O(x^99)) \\ Charles R Greathouse IV, Sep 26 2012
(Magma) I:=[1, 15, 163]; [n le 3 select I[n] else 15*Self(n-1)-62*Self(n-2)+72*Self(n-3): n in [1..20]]; /* or */ m:=20; R<x>:=PowerSeriesRing(Integers(), m); Coefficients(R!(1/((1-2*x)*(1-4*x)*(1-9*x)))); // Vincenzo Librandi, Jun 26 2013
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
STATUS
approved