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 A173250 #3 Mar 30 2012 18:52:39 %S A173250 1,9,21,27,33,49,51,57,63,69,87,91,93,99,117,121,129,141,147,153,169, %T A173250 171,183,187,189,201,213,217,219,231,247,253,259,261,267,273,297,301, %U A173250 303,321,327,339,343,357,363,369,387,391,399,411,423,429,447,451,453 %N A173250 Positive odd nonprimes of the form prime-10. %e A173250 a(1)=1 because 11(prime)-10=1(positive odd nonprime); a(2)=9 because 19(prime)-10=9(positive odd nonprime). %Y A173250 Cf. A000040, A141468, A164384. %K A173250 nonn %O A173250 1,2 %A A173250 _Juri-Stepan Gerasimov_, Feb 14 2010 %E A173250 343 inserted by _R. J. Mathar_, Feb 21 2010