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 A247346 #31 Nov 30 2014 15:32:00 %S A247346 151,201,227,341,403,423,537,605,635,715,805,847,891,909,953,955,1003, %T A247346 1073,1075,1129,1131,1191,1271,1273,1337,1431,1433,1505,1613,1693, %U A247346 1697,1783,1787,1907,1911,2007,2011,2147,2149,2257,2259,2263,2377,2383,2421,2503,2541,2547,2675,2681 %N A247346 Odd numbers n containing 1024 as the highest power of 2 in their Collatz (3x+1) iteration. %C A247346 a(n)*2^k also contains 1024 as the highest of 2 for any k >= 0. %H A247346 Derek Orr, <a href="/A247346/b247346.txt">Table of n, a(n) for n = 1..50</a> %o A247346 (PARI) %o A247346 Max2(n)=v=[n]; while(n!=1, if(n==Mod(0, 2), n=n/2; v=concat(v, n)); if(n==Mod(1, 2)&&n!=1, n=3*n+1; v=concat(v, n))); k=1; while(vecsearch(vecsort(v), 2^k), k++); 2^(k-1) %o A247346 n=1;while(n<10^4,if(n%2&&Max2(n)==1024,print1(n,", "));n++) %Y A247346 Cf. A008908, A010120. %K A247346 nonn %O A247346 1,1 %A A247346 _Derek Orr_, Sep 22 2014