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 A259343 #9 Jul 07 2015 19:35:58 %S A259343 1,3,7,13,25,41,73,127,241,273 %N A259343 A001116(n) + 1. %H A259343 John Tangen, <a href="/A259343/a259343.pdf">Letter to N. J. A. Sloane, Apr 27 1978</a> %Y A259343 Cf. A001116. %K A259343 nonn,more,hard %O A259343 0,2 %A A259343 _N. J. A. Sloane_, Jun 27 2015, following a suggestion from John Tangen, Apr 27 1978