Let u(0)=1, u(n) = 5/2 * floor(u(n-1)); then a(n) = (2/5)*u(n).

Terms

a(0) =1a(1) =2a(2) =5a(3) =12a(4) =30a(5) =75a(6) =187a(7) =467a(8) =1167a(9) =2917a(10) =7292a(11) =18230a(12) =45575a(13) =113937a(14) =284842a(15) =712105a(16) =1780262a(17) =4450655a(18) =11126637a(19) =27816592a(20) =69541480a(21) =173853700a(22) =434634250a(23) =1086585625a(24) =2716464062a(25) =6791160155a(26) =16977900387a(27) =42444750967a(28) =106111877417