a(1) = 2, thereafter a(n) = Sum_{k=1..n-1} floor(a(n-k)/k).

Terms

a(0) =2a(1) =2a(2) =3a(3) =4a(4) =5a(5) =8a(6) =11a(7) =17a(8) =25a(9) =39a(10) =59a(11) =93a(12) =146a(13) =229a(14) =361a(15) =569a(16) =898a(17) =1419a(18) =2243a(19) =3546a(20) =5608a(21) =8869a(22) =14029a(23) =22191a(24) =35105a(25) =55531a(26) =87846a(27) =138967a(28) =219844a(29) =347785