OFFSET
0,3
COMMENTS
Diagonal sums of A112475.
LINKS
Index entries for linear recurrences with constant coefficients, signature (0,2,2,1).
FORMULA
G.f.: (1-x)/((1+x)*(1-x-x^2-x^3)).
a(n) = 2*a(n-2)+2*a(n-3)+a(n-4).
a(n) = Sum_{k=0..floor(n/2)} Sum_{j=0..n-2*k} C(k-1, j)*C(n-k-j-1, n-2*k-j).
CROSSREFS
KEYWORD
easy,sign
AUTHOR
Paul Barry, Sep 07 2005
STATUS
approved