498971881domain: NAppears in sequencesExpansion of e.g.f. exp(x) / (1 - x^4).at n=12A330045a(n) = (4*n)! * Sum_{k=0..n} 1 / (4*k)!.at n=3A337727a(n) = n! * Sum_{k=0..floor(n/4)} 1 / (4*k)!.at n=12A352660