a(n) = Sum_{j=0..n} (-1)^(n-j) * Product_{k=(j-1)*n+1..j*n} k.

A349480

a(n) = Sum_{j=0..n} (-1)^(n-j) * Product_{k=(j-1)*n+1..j*n} k.

Terms

    a(0) =1a(1) =1a(2) =10a(3) =390a(4) =33456a(5) =4845360a(6) =1059099840a(7) =325460948400

External references