a(n) = n! * Sum_{k=0..floor(n/4)} (n - 4*k)^k/(24^k * (n - 4*k)!).

A356608

a(n) = n! * Sum_{k=0..floor(n/4)} (n - 4*k)^k/(24^k * (n - 4*k)!).

Terms

    a(0) =1a(1) =1a(2) =1a(3) =1a(4) =1a(5) =6a(6) =31a(7) =106a(8) =281a(9) =1261a(10) =13861a(11) =106261a(12) =558361a(13) =2709136a(14) =32802771a(15) =447762316a(16) =4093711441a(17) =28011714641a(18) =293624974441

External references