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 A135727 #3 Mar 31 2012 13:48:24 %S A135727 0,2,2,8,4,20,8,20,8,56,20,32,12,56,20,44,16,272,56,56,20,272,32,272, %T A135727 24,272,56,80,28,128,44,272,32,488,272,104,56,272,56,128,40,272,272, %U A135727 128,44,272,272,140,48,488,272 %N A135727 Maximal value in orbit of n under the map A001281(x)=3x-1 if x odd, x/2 if x even. %C A135727 On the set of positive integers, the orbit of any number under A001281 seems to end in the orbit of 2, of 20 or of 272, which are the respective maxima of these cycles. Since any odd number increases under the map A001281, all elements of this sequence are even. %o A135727 (PARI) A135727(n)=local(m=n);if(n, while( n != 272 & n != 20 & n != 2, if( n%2, n=3*n-1; m=max(n,m), n>>=1)));m %Y A135727 Cf. A001281, A037084, A039500-A039505, A135728-A135730. A006370, A006577. %K A135727 nonn %O A135727 0,2 %A A135727 _M. F. Hasler_, Nov 26 2007