OFFSET
0,3
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..300
Index entries for linear recurrences with constant coefficients, signature (2,3).
FORMULA
a(n)=Sum{k=1..n, Binomial(n, 2k-2)2^(2k-2)}
a(n)=(3^n-2*0^n+(-1)^n)/2; G.f.: x(1+3x)/((1+x)(1-3x)); E.g.f.: (exp(3x)-2exp(0)+exp(-x))/2. - Paul Barry, May 19 2003
MATHEMATICA
CoefficientList[Series[x (1 + 3 x) / ((1 + x) (1 - 3 x)), {x, 0, 40}], x] (* Vincenzo Librandi, Aug 05 2013 *)
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Paul Barry, Feb 26 2003
STATUS
approved