a(1)=1, a(n) = n*6^(n-1) + a(n-1).

Terms

a(0) =1a(1) =13a(2) =121a(3) =985a(4) =7465a(5) =54121a(6) =380713a(7) =2620201a(8) =17736745a(9) =118513705a(10) =783641641a(11) =5137206313a(12) =33435376681a(13) =216285092905