Floor( phi * (3/2)^n ) where phi = (1+sqrt(5))/2.

Terms

a(0) =1a(1) =2a(2) =3a(3) =5a(4) =8a(5) =12a(6) =18a(7) =27a(8) =41a(9) =62a(10) =93a(11) =139a(12) =209a(13) =314a(14) =472a(15) =708a(16) =1062a(17) =1594a(18) =2391a(19) =3586a(20) =5380a(21) =8070a(22) =12105a(23) =18158a(24) =27238a(25) =40857a(26) =61285a(27) =91928a(28) =137893a(29) =206839