A337150 Nonnegative integers in the order in which they appear first in A006577.
0, 1, 7, 2, 5, 8, 16, 3, 19, 6, 14, 9, 17, 4, 12, 20, 15, 10, 23, 111, 18, 106, 26, 13, 21, 34, 109, 29, 104, 11, 24, 112, 32, 107, 27, 102, 22, 115, 35, 110, 30, 92, 105, 118, 25, 87, 38, 100, 113, 69, 33, 95, 46, 108, 121, 28, 41, 90, 103, 116, 36, 85, 54
Offset: 1
Links
Programs
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Maple
collatz:= proc(n) option remember; `if`(n=1, 0, 1 + collatz(`if`(n::even, n/2, 3*n+1))) end: b:= proc() 0 end: g:= proc(n) option remember; local t; `if`(n=1, 0, g(n-1)); t:= collatz(n); b(t):= b(t)+1 end: h:= proc(n) option remember; local k; for k from 1+h(n-1) while g(k)>1 do od; k end: h(0):=0: a:= n-> collatz(h(n)): seq(a(n), n=1..100); -
Mathematica
collatz[n_] := collatz[n] = If[n==1, 0, 1 + collatz[If[EvenQ[n], n/2, 3n+1]]]; b[_] = 0; g[n_] := g[n] = Module[{t}, If[n==1, 0, g[n-1]]; t = collatz[n]; b[t] = b[t]+1]; h[n_] := h[n] = Module[{k}, For[k = 1+h[n-1], g[k]>1, k++]; k]; h[0] = 0; a[n_] := a[n] = collatz[h[n]]; Array[a, 100] (* Jean-François Alcover, Jan 30 2021, after Alois P. Heinz *)
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