a(n) = floor(11^n/6^n).

Terms

a(0) =1a(1) =1a(2) =3a(3) =6a(4) =11a(5) =20a(6) =37a(7) =69a(8) =127a(9) =233a(10) =428a(11) =786a(12) =1441a(13) =2643a(14) =4845a(15) =8884a(16) =16287a(17) =29861a(18) =54745a(19) =100366a(20) =184004a(21) =337341a(22) =618459a(23) =1133843a(24) =2078712a(25) =3810972a(26) =6986783a(27) =12809103a(28) =23483356a(29) =43052820