a(n) = n! * Sum_{k=0..floor(n/4)} k^k / (k! * (n-4*k)!).

A362349

a(n) = n! * Sum_{k=0..floor(n/4)} k^k / (k! * (n-4*k)!).

Terms

    a(0) =1a(1) =1a(2) =1a(3) =1a(4) =25a(5) =121a(6) =361a(7) =841a(8) =82321a(9) =728785a(10) =3633841a(11) =13313521a(12) =2195435881a(13) =28125394441a(14) =196393341145a(15) =981274727161

External references