A243628 Odd numbers producing 30 even numbers in the Collatz iteration.

185, 187, 191, 541, 545, 551, 557, 561, 563, 575, 607, 1629, 1635, 1637, 1655, 1659, 1671, 1677, 1681, 1683, 1685, 1687, 1725, 1755, 1803, 1821, 1825, 1833, 2007, 2011, 4885, 4917, 4929, 4953, 4963, 4965, 4979, 5015, 5017, 5029, 5041, 5043, 5045, 5061, 5077, 5081, 5091, 5121

Offset: 1

Author

Vincenzo Librandi, Jun 08 2014

Keywords

• nonn
• fini
• less

Comments

See row 30 of A199636.

Links

• Vincenzo Librandi, Table of n, a(n) for n = 1..697

Crossrefs

Cf. A199636, A199817, A199818.

Programs

Mathematica

Collatz[n_] := NestWhileList[If[EvenQ[#], #/2, 3 # + 1] &, n, # > 1 &]; t = {}; Do[If[Length[Select[Collatz[n], EvenQ]] == 30, AppendTo[t, n]], {n, 1, 100000, 2}]; t
on30Q[n_]:=Count[NestWhileList[If[EvenQ[#],#/2,3#+1]&,n,#!=1&],?EvenQ] ==30; Select[Range[1,5131,2],on30Q] (* _Harvey P. Dale, Mar 18 2023 *)