a(n) = n! * Sum_{k=0..floor(n/4)} (n - 4*k)^k/(n - 4*k)!.
A356630
a(n) = n! * Sum_{k=0..floor(n/4)} (n - 4*k)^k/(n - 4*k)!.
Terms
- a(0) =1a(1) =1a(2) =1a(3) =1a(4) =1a(5) =121a(6) =721a(7) =2521a(8) =6721a(9) =378001a(10) =7287841a(11) =59930641a(12) =319429441a(13) =7524471241a(14) =353072319601
External references
- oeis: A356630