a(n) = n! * Sum_{k=0..floor(n/2)} (-1)^k / (n-2*k)!.

A337749

a(n) = n! * Sum_{k=0..floor(n/2)} (-1)^k / (n-2*k)!.

Terms

    a(0) =1a(1) =1a(2) =-1a(3) =-5a(4) =13a(5) =101a(6) =-389a(7) =-4241a(8) =21785a(9) =305353a(10) =-1960649a(11) =-33588829a(12) =258805669a(13) =5239857325a(14) =-47102631757

External references