OFFSET
2,1
LINKS
Index entries for linear recurrences with constant coefficients, signature (13,-39,27).
FORMULA
a(n) =3*A006100(n).
From Colin Barker, Aug 15 2014: (Start)
a(n) = (3-4*3^n+9^n)/16.
a(n) = 13*a(n-1)-39*a(n-2)+27*a(n-3).
G.f.: -3*x^2 / ((x-1)*(3*x-1)*(9*x-1)). (End)
MATHEMATICA
PROG
(PARI) Vec(-3*x^2/((x-1)*(3*x-1)*(9*x-1)) + O(x^100)) \\ Colin Barker, Aug 15 2014
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Clark Kimberling, Dec 31 2011
STATUS
approved