OFFSET
0,2
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..200
Index entries for linear recurrences with constant coefficients, signature (23,-174,432).
FORMULA
a(n) = 6*6^n -32*8^n +27*9^n. - R. J. Mathar, Jun 30 2013
a(0)=1, a(1)=23, a(2)=355; for n>2, a(n) = 23*a(n-1) -174*a(n-2) +432*a(n-3). - Vincenzo Librandi, Jul 04 2013
a(n) = 17*a(n-1) -72*a(n-2) +6^n. - Vincenzo Librandi, Jul 04 2013
MATHEMATICA
CoefficientList[Series[1 / ((1 - 6 x) (1 - 8 x) (1 - 9 x)), {x, 0, 20}], x] (* Vincenzo Librandi, Jul 04 2013 *)
PROG
(Magma) m:=20; R<x>:=PowerSeriesRing(Integers(), m); Coefficients(R!(1/((1-6*x)*(1-8*x)*(1-9*x)))); /* or */ I:=[1, 23, 355]; [n le 3 select I[n] else 23*Self(n-1)-174*Self(n-2)+432*Self(n-3): n in [1..20]]; // Vincenzo Librandi, Jul 04 2013
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
STATUS
approved