100451domain: NAppears in sequencesa(n) = binomial(n,0) - binomial(n,2) + binomial(n,4).at n=41A058923Principal diagonal of the convolution array A213773.at n=25A214092a(n) = [x^n] Product_{k>=2} 1/(1 - x^k)^n.at n=12A319670