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 A129740 #7 Sep 14 2017 04:36:10 %S A129740 4,5,6,7,8,11,13,16,43,52,206,647 %N A129740 Indices of primes in Somos-4 sequence (A006720). %C A129740 Sequence is probably finite - see A006720. %H A129740 G. Everest et al., <a href="http://www.jstor.org/stable/27642221">Primes generated by recurrence sequences</a>, Amer. Math. Monthly, 114 (No. 5, 2007), 417-431. %Y A129740 Cf. A006720, A129739, A129741. %K A129740 nonn,more %O A129740 1,1 %A A129740 _N. J. A. Sloane_, May 13 2007 %E A129740 More terms (based on the entry A006720) from _Stefan Steinerberger_, Jun 06 2007