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 A187684 #4 Mar 30 2012 18:57:19 %S A187684 3,6,10,12,16,19,21,25,29,32,34,38,41,45,49,51,54,58,60,63,67,69,73, %T A187684 77,80,82,86,89,93,95,98,102,104,107,111,115,117,121,124,126,130,134, %U A187684 137,141,143,146,150,154,156,159,163,165,168,172,174,178,182,185,187,191,194,198,200,203,207,211,213,217 %N A187684 Complement of A187683. %C A187684 See A187224. %t A187684 (See A187683.) %Y A187684 Cf. A197224, A187683. %K A187684 nonn %O A187684 1,1 %A A187684 _Clark Kimberling_, Mar 12 2011