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 A151891 #6 Mar 13 2020 12:51:12 %S A151891 2,4,9,36,6561,252252704150178,1650016588712720468 %N A151891 a(n) = Pi(A113824(n+1)). %H A151891 Kim Walisch, <a href="https://github.com/kimwalisch/primecount">Fast C++ prime counting function implementation (primecount)</a>. %Y A151891 Cf. A073924, A080355, A080567, A099969, A099970, A099971, A099972, A113824. %K A151891 nonn,more %O A151891 1,1 %A A151891 _Artur Jasinski_, Apr 04 2008 %E A151891 a(6)-a(7) using Kim Walisch's primecount, from _Amiram Eldar_, Mar 13 2020