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 A039501 #10 Dec 19 2015 12:56:53 %S A039501 5,7,9,10,13,14,18,19,20,26,27,28,35,36,38,40,47,51,52,54,56,63,70,72, %T A039501 75,76,80,81,89,93,94,102,104,107,108,112,119,121,125,126,133,139,140, %U A039501 143,144,149,150,152,159,160,161,162,167,177,178,181,186,187,188,191 %N A039501 Iterations of "n->n/2 if n even, n->3n-1 if n odd" (A001281) starting at these numbers reach 5. %t A039501 it5Q[n_]:=Last[NestWhileList[If[EvenQ[#],#/2,3#-1]&,n,#!=5&,1,100]]==5; Select[Range[200],it5Q] (* _Harvey P. Dale_, May 09 2012 *) %Y A039501 Cf. A037084, A039500-A039505. %K A039501 nonn,easy %O A039501 1,1 %A A039501 _Christian G. Bower_, Feb 15 1999