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 A058133 #19 Oct 27 2019 14:27:46 %S A058133 0,1,2,6,27,156,1373,17730,858977,1844075697,52991253973742 %N A058133 Number of monoids (semigroups with identity) of order n, considered to be equivalent when they are isomorphic or anti-isomorphic (by reversal of the operator). %H A058133 Eric Postpischil <a href="https://groups.google.com/d/msg/sci.math/nU-hg-FFSFo/iIB3Lul1sAEJ">Posting to sci.math newsgroup, May 21 1990</a> %H A058133 Andreas Distler and Tom Kelsey, <a href="https://doi.org/10.1007/978-3-540-85110-3_7">The Monoids of Order Eight and Nine</a>. Lecture Notes in Computer Science 5144 (2008), 61-76. %H A058133 Andreas Distler and Tom Kelsey, <a href="https://doi.org/10.1007/s10472-009-9140-y">The Monoids of Orders Eight, Nine & Ten</a>. Annals of Mathematics and Artificial Intelligence 56 (2009), 3-25. %H A058133 <a href="/index/Mo#monoids">Index entries for sequences related to monoids</a> %F A058133 a(n)=(A058129(n)+A058132(n))/2. %Y A058133 Cf. A001423, A058129, A058132, A151823. %K A058133 nonn,more,hard %O A058133 0,3 %A A058133 _Christian G. Bower_, Nov 13 2000 %E A058133 a(8) and a(9) from Distler & Kelsey (2008), added by _N. J. A. Sloane_, Jul 10 2009 %E A058133 a(10) from Distler & Kelsey (2009), added by _Max Alekseyev_, Jul 13 2009 %E A058133 a(0) prepended by _Jianing Song_, Oct 26 2019