a(n) = n! * Sum_{d|n} (-1)^(n - d) / (n/d)!^d.

A327587

a(n) = n! * Sum_{d|n} (-1)^(n - d) / (n/d)!^d.

Terms

    a(0) =1a(1) =1a(2) =7a(3) =29a(4) =121a(5) =649a(6) =5041a(7) =42909a(8) =364561a(9) =3515651a(10) =39916801a(11) =486821873a(12) =6227020801a(13) =86497214231

External references