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 A173311 #21 Jun 12 2022 16:14:14
%S A173311 1,2,4,9,25,88,406,2451,19450,202681,2769965,49519392,1154411138,
%T A173311 34978238590,1373171398361,69648249299517,4552778914494604
%N A173311 a(n) is the number of regular D classes in the semigroup of all binary relations on [n].
%C A173311 Previous name was: Partial sums of A000112.
%H A173311 K. K.-H. Butler and G. Markowsky, <a href="https://www.koreascience.or.kr/article/JAKO197225748110925.pdf">The Number of Maximal Subgroups of the Semigroup of Binary Relations</a>, Kyungpook Math. J. Vol 12, June 1972.
%F A173311 a(n) = Sum_{i=0..n} A000112(i).
%t A173311 Cases[Import["https://oeis.org/A000112/b000112.txt", "Table"], {_, _}][[All, 2]] // Accumulate (* _Jean-François Alcover_, Jan 01 2020 *)
%Y A173311 Cf. A000112, A000798 (labeled topologies), A001035 (labeled posets), A001930 (unlabeled topologies), A006057, A079263, A079265, A007903.
%K A173311 nonn,hard,more
%O A173311 0,2
%A A173311 _Jonathan Vos Post_, Feb 16 2010
%E A173311 New name from _Geoffrey Critzer_, May 22 2022