This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A176869 #3 Mar 30 2012 17:22:56 %S A176869 1,16,40,52,64,88,100,112,136,148,160,184,196,208,232,244,256,280,304, %T A176869 340,352,400,424,448,472,520,532,544,592,616,628,640,688,712,724,736, %U A176869 784,808,820,832,868,904,916,928,952,964,976,1024,1048,1072,1108,1120 %N A176869 Numbers that are the maximum value attained by the Collatz (3x+1) iteration of some odd number. %C A176869 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. %H A176869 T. D. Noe, <a href="/A176869/b176869.txt">Table of n, a(n) for n=1..1000</a> %Y A176869 Cf. A025586 (maximum value in the Collatz iteration of n) %K A176869 nonn %O A176869 1,2 %A A176869 _T. D. Noe_, Apr 27 2010