a(n) = (n!)^2 * Sum_{d|n} 1 / (d!)^2.

A336241

a(n) = (n!)^2 * Sum_{d|n} 1 / (d!)^2.

Terms

    a(0) =1a(1) =5a(2) =37a(3) =721a(4) =14401a(5) =662401a(6) =25401601a(7) =2034950401a(8) =135339724801

External references