A222600 Least number k such that the difference between the number of halving and tripling steps in the Collatz (3x+1) iteration is n.

1, 2, 4, 3, 6, 12, 7, 9, 18, 25, 33, 43, 39, 78, 105, 135, 123, 169, 159, 295, 283, 111, 222, 297, 175, 103, 91, 121, 31, 27, 54, 73, 97, 129, 171, 231, 313, 411, 543, 327, 649, 859, 763, 1017, 1351, 1215, 703, 937, 871, 1161, 2223, 3097, 2631, 3567, 3175, 4233

Offset

0,2

Comments

This is the first number in row n of A222599.

Links

T. D. Noe, Table of n, a(n) for n = 0..264 (searching until the Collatz sequence has a term greater than 2^63)

Mathematica

Collatz[n_] := NestWhileList[If[EvenQ[#], #/2, 3 # + 1] &, n, # > 1 &]; nn = 50; t = Table[0, {nn}]; n = 0; While[Min[t] == 0, n++; c = Collatz[n]; e = Select[c, EvenQ]; diff = 2*Length[e] - Length[c]; If[diff < nn - 1 && t[[diff + 2]] == 0, t[[diff + 2]] = n]]; t

Crossrefs

Cf. A213678, A222599.

Sequence in context: A225055 A341194 A120947 * A046793 A182940 A101278

Adjacent sequences: A222597 A222598 A222599 * A222601 A222602 A222603

Keyword

nonn

Author

T. D. Noe, Mar 04 2013

Status

approved