A176869 Numbers that are the maximum value attained by the Collatz (3x+1) iteration of some odd number.

1, 16, 40, 52, 64, 88, 100, 112, 136, 148, 160, 184, 196, 208, 232, 244, 256, 280, 304, 340, 352, 400, 424, 448, 472, 520, 532, 544, 592, 616, 628, 640, 688, 712, 724, 736, 784, 808, 820, 832, 868, 904, 916, 928, 952, 964, 976, 1024, 1048, 1072, 1108, 1120

Offset

1,2

Comments

Here the 3x+1 steps and the halving steps are applied separately. We use odd numbers because then the Collatz iteration always increases to a maximum value before (hopefully) going to 1. This is a subsequence of A033496. Except for the first term, all these numbers appear to equal 4 (mod 12). Some terms are the maximum value for the Collatz iteration of many numbers. For example, 9232 is the maximum value of the Collatz iteration of 408 odd numbers, the smallest of which is 27.

Links

T. D. Noe, Table of n, a(n) for n=1..1000

Crossrefs

Cf. A025586 (maximum value in the Collatz iteration of n)

Sequence in context: A253698 A185769 A205255 * A132161 A316562 A221684

Adjacent sequences: A176866 A176867 A176868 * A176870 A176871 A176872

Keyword

nonn

Author

T. D. Noe, Apr 27 2010

Status

approved