a(n) = floor(11^n/5^n).

Terms

a(0) =1a(1) =2a(2) =4a(3) =10a(4) =23a(5) =51a(6) =113a(7) =249a(8) =548a(9) =1207a(10) =2655a(11) =5843a(12) =12855a(13) =28281a(14) =62218a(15) =136880a(16) =301136a(17) =662499a(18) =1457498a(19) =3206497a(20) =7054294a(21) =15519448a(22) =34142787a(23) =75114133a(24) =165251092a(25) =363552403a(26) =799815288a(27) =1759593634a(28) =3871105995a(29) =8516433190