a(n) = floor(5^n/4^(n-1)).

Terms

a(0) =5a(1) =6a(2) =7a(3) =9a(4) =12a(5) =15a(6) =19a(7) =23a(8) =29a(9) =37a(10) =46a(11) =58a(12) =72a(13) =90a(14) =113a(15) =142a(16) =177a(17) =222a(18) =277a(19) =346a(20) =433a(21) =542a(22) =677a(23) =847a(24) =1058a(25) =1323a(26) =1654a(27) =2067a(28) =2584a(29) =3231