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 A006123 M1215 #21 Mar 08 2018 03:47:52 %S A006123 1,1,2,4,10,26,75,215 %N A006123 Erroneous version of A000085. %C A006123 Computation of tree based structure as detailed in Mallows Jun 1991 letter produces A000085. - _Sean A. Irvine_, Mar 06 2018 %D A006123 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). %H A006123 C. L. Mallows & N. J. A. Sloane, <a href="/A006123/a006123.pdf">Emails, May 1991</a> %H A006123 C. L. Mallows & N. J. A. Sloane, <a href="/A006123/a006123_1.pdf">Emails, Jun. 1991</a> %K A006123 dead %O A006123 0,3 %A A006123 _Colin Mallows_