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 A058108 #21 Jan 14 2024 08:56:53 %S A058108 1,2,3,5,9,10,20,50,72,46,171,309,590,594,251,5284,2806,5422,7772, %T A058108 5668,1682,1224331,58583,61323,101539,109107,59576,13213,3667785000, %U A058108 9207430,1150085,1466691,1983558,1626956,690871,119826,105952488687468,25412267163,136799017,27690828,36991211,39865274,25666762,8739857,1228712 %N A058108 Triangle read by rows: number of nonisomorphic semigroups of order n with k idempotents. %H A058108 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 A058108 A. Distler and T. Kelsey, <a href="http://arxiv.org/abs/1301.6023">The semigroups of order 9 and their automorphism groups</a>, arXiv preprint arXiv:1301.6023 [math.CO], 2013. %H A058108 <a href="/index/Se#semigroups">Index entries for sequences related to semigroups</a> %e A058108 Triangle begins: %e A058108 1; %e A058108 2, 3; %e A058108 5, 9, 10; %e A058108 20, 50, 72, 46; %e A058108 171, 309, 590, 594, 251; %e A058108 ... %Y A058108 Row sums give A027851. Main diagonal: A058112. Columns 1-3: A058109-A058111. %K A058108 nonn,tabl,hard %O A058108 1,2 %A A058108 _Christian G. Bower_, Nov 09 2000 %E A058108 Updated Feb 19 2001 %E A058108 More terms from _Andreas Distler_, Jan 13 2011