a(n) = ((n^2 + 1)^n - 1)/n^3.A175771a(n) = ((n^2 + 1)^n - 1)/n^3.Terms a(0) =1a(1) =3a(2) =37a(3) =1305a(4) =95051a(5) =11878363a(6) =2277696793a(7) =622353150177External referencesoeis: A175771