a(n) is the sum of all positive integers whose Collatz orbit has length n.

Terms

a(0) =0a(1) =1a(2) =2a(3) =4a(4) =8a(5) =16a(6) =37a(7) =74a(8) =172a(9) =344a(10) =786a(11) =1572a(12) =3538a(13) =7206a(14) =16252a(15) =33112a(16) =73762a(17) =149967a(18) =330107a(19) =678610a(20) =1498356a(21) =3082302a(22) =6742487a(23) =13855154a(24) =30122440a(25) =62388962a(26) =135783788a(27) =281177482a(28) =608402189a(29) =1259151448