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 A349401 #20 Jul 18 2022 13:13:41 %S A349401 0,0,1,2,6,19,80,395,2487,19890,206565,2804453,49872647,1158843214, %T A349401 35049606566,1374685228988,69690886873398,4554367168841547 %N A349401 Number of unlabeled disconnected posets with n elements. %H A349401 Gunnar Brinkmann and Brendan D. McKay, <a href="http://users.cecs.anu.edu.au/~bdm/papers/posets.pdf">Posets on up to 16 points</a>. %H A349401 Salah Uddin Mohammad, Md. Shah Noor, and Md. Rashed Talukder, <a href="https://cs.uwaterloo.ca/journals/JIS/VOL25/Uddin/uddin6.html">An Exact Enumeration of the Unlabeled Disconnected Posets</a>, J. Int. Seq., Vol. 25 (2022), Article 22.5.4. %F A349401 a(n) = A000112(n) - A000608(n). %Y A349401 Cf. A000112, A000608, A342500. %K A349401 nonn,more %O A349401 0,4 %A A349401 _Salah Uddin Mohammad_, Nov 15 2021