Number of typable lambda terms of size n with size 0 for the variables.

Terms

a(0) =0a(1) =0a(2) =1a(3) =1a(4) =2a(5) =2a(6) =3a(7) =5a(8) =8a(9) =13a(10) =22a(11) =36a(12) =58a(13) =103a(14) =177a(15) =307a(16) =535a(17) =949a(18) =1645a(19) =2936a(20) =5207a(21) =9330a(22) =16613a(23) =29921a(24) =53588a(25) =96808a(26) =174443a(27) =316267a(28) =572092a(29) =1040596