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 A109894 #15 Nov 04 2018 13:12:11 %S A109894 1,20,4620,12697776,159845400,941432800,158800433792,1895312483064000, %T A109894 3438271897004237230080,933561026438040,2562849175892544, %U A109894 640904462719404383808000,1528364130975,2352733350786,959393282698730880000,6142080926952 %N A109894 Duplicate of A079759. %K A109894 dead %O A109894 1,2