a(n) = (-1)^n*Sum((-1)^j*b(j), j=1..n), where b(n)=(n-1)!*(n^2 - n + 1) = A001564(n-1) (n>=1).

A180195

a(n) = (-1)^n*Sum((-1)^j*b(j), j=1..n), where b(n)=(n-1)!*(n^2 - n + 1) = A001564(n-1) (n>=1).

Terms

    a(0) =1a(1) =2a(2) =12a(3) =66a(4) =438a(5) =3282a(6) =27678a(7) =259602a(8) =2683758a(9) =30338322a(10) =372458478a(11) =4936475922a(12) =70266775278

External references