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 A139013 #4 Mar 30 2012 17:26:27 %S A139013 3,5,6,12,21,24,31,36,42,45,55,60,61,87,102,104,110,116,120,132,153, %T A139013 163,168,186,193,204,205,222,227,228,234,235,237,261,273,275,297,300, %U A139013 315,320,321,343,370,375,381,383,394,401,426,438,441,460,468,485,486,489 %N A139013 a(n) = A074924(n)/2. %H A139013 Zak Seidov, <a href="/A139013/b139013.txt">Table of n, a(n) for n = 1..1000.</a> %Y A139013 Cf. A074924. %K A139013 nonn %O A139013 1,1 %A A139013 _Zak Seidov_, Apr 06 2008