a(n) = 11*6^n+1.

Terms

a(0) =12a(1) =67a(2) =397a(3) =2377a(4) =14257a(5) =85537a(6) =513217a(7) =3079297a(8) =18475777a(9) =110854657a(10) =665127937a(11) =3990767617a(12) =23944605697a(13) =143667634177a(14) =862005805057