a(n) = n! * Sum_{k=0..n} binomial(n*k,n-k)/k!.

A361281

a(n) = n! * Sum_{k=0..n} binomial(n*k,n-k)/k!.

Terms

    a(0) =1a(1) =1a(2) =5a(3) =37a(4) =481a(5) =10001a(6) =288901a(7) =10820965a(8) =511186817a(9) =29843419681

External references