OFFSET
0,3
COMMENTS
Diagonal sums of A111960.
FORMULA
a(n)=sum{k=0..floor(n/2), sum{j=0..n-k, C(n-k, j)*C((j-1)/2, (j-k)/2)*2^(j-k)*(1+(-1)^(j-k))/2}}
D-finite with recurrence: n*a(n) +(-4*n+3)*a(n-1) +(-2*n+3)*a(n-2) +3*(4*n-9)*a(n-3) +(8*n-27)*a(n-4) +(2*n-3)*a(n-5) +3*(n-3)*a(n-6)=0. - R. J. Mathar, Jan 24 2020
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Paul Barry, Aug 23 2005
STATUS
approved