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

Terms

a(0) =1a(1) =7a(2) =73a(3) =649a(4) =5185a(5) =38881a(6) =279937a(7) =1959553a(8) =13436929a(9) =90699265a(10) =604661761a(11) =3990767617a(12) =26121388033a(13) =169789022209