a(n) = cardinality of a certain set of natural numbers defined using A117818.

Terms

a(0) =1a(1) =2a(2) =3a(3) =4a(4) =6a(5) =8a(6) =12a(7) =18a(8) =25a(9) =38a(10) =56a(11) =89a(12) =138a(13) =218a(14) =342a(15) =547a(16) =882a(17) =1429a(18) =2299a(19) =3705a(20) =5961a(21) =9615a(22) =15524a(23) =25057a(24) =40442a(25) =65247a(26) =105412a(27) =170224a(28) =274963a(29) =44156