Number of new duplicate terms at a given iteration of the Collatz (or 3x+1) map starting with 0.

Terms

a(0) =0a(1) =0a(2) =0a(3) =0a(4) =1a(5) =1a(6) =2a(7) =4a(8) =8a(9) =16a(10) =34a(11) =67a(12) =137a(13) =272a(14) =540a(15) =1061a(16) =2074a(17) =4022a(18) =7763a(19) =14914a(20) =28556a(21) =54499a(22) =103729a(23) =196945a(24) =373201a(25) =705964a(26) =1333413a(27) =2515260a(28) =4739233a(29) =8920743