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 A138786 #5 Mar 30 2012 18:52:52 %S A138786 9,21,25,27,35,45,49,55,69,75,77,81,93,95,99,105,115,119,121,125,133, %T A138786 135,141,143,147,153,155,161,165,169,175,187,189,203,207,209,213,215, %U A138786 217,219,221,225,231,235,237,243,245,247,253,259,261,267,279,285,287 %N A138786 "Left" odd composite numbers n for which n < A140607((n-1)/2). %C A138786 There are odd composite numbers which are neither in this sequence nor in A140608. The first such number is 91, see A140667. %H A138786 Ray Chandler, <a href="/A138786/b138786.txt">Table of n, a(n) for n=1..5713</a> %Y A138786 Cf. A140607, A039649, A140140, A138193, A138217, A138227, A138535, A138536, A138537, A138539, A140141, A000010, A000040, A140608, A140667. %K A138786 nonn %O A138786 1,1 %A A138786 _Vladimir Shevelev_, May 18 2008 %E A138786 Extended by _Ray Chandler_, May 20 2008