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 A278740 #5 Nov 27 2016 21:48:35 %S A278740 577,5569,29251 %N A278740 Primes in A138290. %Y A278740 Cf. A138290. %K A278740 nonn,more,hard,bref %O A278740 1,1 %A A278740 _Hans Havermann_, Nov 27 2016