Number of orbits of length n under the map whose periodic points are counted by A001643.

Terms

a(0) =1a(1) =1a(2) =1a(3) =2a(4) =4a(5) =6a(6) =10a(7) =15a(8) =26a(9) =42a(10) =74a(11) =121a(12) =212a(13) =357a(14) =620a(15) =1064a(16) =1856a(17) =3209a(18) =5618a(19) =9794a(20) =17192a(21) =30153a(22) =53114a(23) =93554a(24) =165308a(25) =292250a(26) =517802a(27) =918207a(28) =1630932a(29) =2899434