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 A107864 #6 Jan 17 2020 23:02:19 %S A107864 1,3,21,220,3060,53130,1107568,26978328,752538150,23667689815, %T A107864 828931106355,32006008361808,1350990969850340,61902409203193230, %U A107864 3060335715568296000,162392216278033616560,9206887338937200407418 %N A107864 Duplicate of A099121. %K A107864 dead %O A107864 0,2 %A A107864 _Paul D. Hanna_, Jun 04 2005