a(n) = Sum_{k=0..floor(n/2)} (-1)^k * (n-2*k)!.
A358607
a(n) = Sum_{k=0..floor(n/2)} (-1)^k * (n-2*k)!.
Terms
- a(0) =1a(1) =1a(2) =1a(3) =5a(4) =23a(5) =115a(6) =697a(7) =4925a(8) =39623a(9) =357955a(10) =3589177a(11) =39558845a(12) =475412423a(13) =6187461955a(14) =86702878777
External references
- oeis: A358607