a(n) = n! * [x^n] exp(Sum_{k=1..n} sigma_n(k) * x^k).

A294388

a(n) = n! * [x^n] exp(Sum_{k=1..n} sigma_n(k) * x^k).

Terms

    a(0) =1a(1) =1a(2) =11a(3) =223a(4) =12193a(5) =1548841a(6) =501460531a(7) =355752425239

External references