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 A029851 #23 Jun 19 2025 20:31:20 %S A029851 1,1,3,12,64,405,3312,44370,2209839,623492664 %N A029851 Number of self-converse semigroups of order n. %H A029851 Andreas Distler, <a href="http://hdl.handle.net/10023/945">Classification and Enumeration of Finite Semigroups</a>, A Thesis Submitted for the Degree of PhD, University of St Andrews (2010). %H A029851 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/Semigroup.html">SemiGroup.</a> %H A029851 <a href="/index/Se#semigroups">Index entries for sequences related to semigroups</a> %F A029851 a(n) = A001423(n)*2 - A027851(n). %Y A029851 Cf. A001423, A001426, A027851. %K A029851 nonn,hard,more,nice %O A029851 0,3 %A A029851 _Christian G. Bower_, Jan 27 1998, updated Feb 19 2001 %E A029851 a(8) and a(9) from _Andreas Distler_, Jan 17 2011