a(n) = 9*6^n+1.

Terms

a(0) =10a(1) =55a(2) =325a(3) =1945a(4) =11665a(5) =69985a(6) =419905a(7) =2519425a(8) =15116545a(9) =90699265a(10) =544195585a(11) =3265173505a(12) =19591041025a(13) =117546246145a(14) =705277476865