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 A233430 #6 Feb 07 2017 17:30:09 %S A233430 1,27950,7845888732,2440547587954985,761939299852168617616, %T A233430 237901286831883052707985079,74280211349600198206855422647223, %U A233430 23192594468009753324332443890051572285,7241449792690453645696899431118614611440302,2261005988402064534018912069618412264537768750810 %N A233430 Number of tilings of a 6 X 5n rectangle with 6n pentominoes of any shape. %H A233430 Wikipedia, <a href="https://en.wikipedia.org/wiki/Pentomino">Pentomino</a> %Y A233430 Quintisection of column k=6 of A233427. %K A233430 nonn %O A233430 0,2 %A A233430 _Alois P. Heinz_, Dec 09 2013