OFFSET
0,5
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (6,-1,-24,9).
FORMULA
a(n) = (1/30)(3^n*Fibonacci(n) - 3*Fibonacci(2n)). - Ralf Stephan, May 14 2004
G.f.: x^3/((1-3*x+x^2)*(1-3*x-9*x^2)). - Colin Barker, Mar 19 2012
MATHEMATICA
CoefficientList[Series[x^3/((1-3*x+x^2)*(1-3*x-9*x^2)), {x, 0, 30}], x] (* Vincenzo Librandi, Mar 20 2012 *)
PROG
(PARI) a(n)=(3^n*fibonacci(n)-3*fibonacci(2*n))/30 \\ Charles R Greathouse IV, Mar 20 2012
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
STATUS
approved