OFFSET
0,2
COMMENTS
Diagonal sums of number triangle A115282.
LINKS
Index entries for linear recurrences with constant coefficients, signature (1,1,0,-1,-1,1).
FORMULA
G.f.: (1+2x)(1+2x^2)/((1-x)(1-x^2)(1-x^3)); a(n)=sum{k=0..floor(n/2), sum{j=0..n-k, [j<=k]*(3-2*0^(k-j))*[j<=n-2k]*(3-2*0^(n-2k-j))}}.
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Paul Barry, Jan 19 2006
STATUS
approved