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 A209600 #15 Apr 01 2015 17:34:31 %S A209600 1,3,2,16,17,21,24,26,29,412,788,1045,369625,369636 %N A209600 Analog of A048613 based on sum of reciprocals of Mersenne primes. %H A209600 M. Wolf, <a href="http://arxiv.org/abs/1112.2412">Computer experiments with Mersenne primes</a>, arXiv preprint arXiv:1112.2412, 2011 %Y A209600 Cf. A048613, A173898, A000668, A209601. %K A209600 nonn,more %O A209600 1,2 %A A209600 _N. J. A. Sloane_, Mar 10 2012