OFFSET
0,2
LINKS
FORMULA
G.f.: (1-2x)/((1-2x)^2-3x^3); a(n)=sum{k=0..floor(n/3), binomial(n-k, 2k)3^k*2^(n-3k)}.
a{x}=1/7(-Cos[(Pi*x)/3]+Cosh[x*Log[3]]+3*Sqrt[3]*Sin[(Pi*x)/3]+Sinh[x*Log[3]]) - Harvey P. Dale, Mar 02 2013
MATHEMATICA
LinearRecurrence[{4, -4, 3}, {1, 2, 4}, 30] (* Harvey P. Dale, Mar 02 2013 *)
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Paul Barry, Oct 06 2004
STATUS
approved