OFFSET
0,2
COMMENTS
In general 1/(1-a*x-b*x^4) expands to sum{k=0..floor(n/4),C(n-3k,k)b^(n-3k)(a/b)^(n-4k)}.
LINKS
Index entries for linear recurrences with constant coefficients, signature (2,0,0,3).
FORMULA
a(n)=2a(n-1)+3a(n-4); a(n)=sum{k=0..floor(n/4), binomial(n-3k, k)3^(n-3k)(2/3)^(n-4k)}.
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Paul Barry, Oct 20 2004
STATUS
approved