Sequence satisfies T(T(a))=a, where T is defined below.

Terms

a(0) =1a(1) =1a(2) =1a(3) =2a(4) =2a(5) =3a(6) =4a(7) =5a(8) =6a(9) =8a(10) =10a(11) =12a(12) =15a(13) =17a(14) =21a(15) =26a(16) =30a(17) =36a(18) =43a(19) =49a(20) =58a(21) =69a(22) =79a(23) =91a(24) =106a(25) =122a(26) =140a(27) =161a(28) =183a(29) =209