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 A047676 #6 Mar 07 2020 01:36:09 %S A047676 1,4,2304,584325558976905216, %T A047676 35313389841821364727572472840336561596134691007780285818034354666813122266941990584103364198400 %N A047676 Main diagonal of square array defined in A047675. %K A047676 nonn %O A047676 0,2 %A A047676 _N. J. A. Sloane_