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 A358391 #14 Nov 22 2022 22:27:32 %S A358391 2,3,10,234,2342196 %N A358391 The number of antichains in the Kreweras lattice of non-crossing set partitions of an n-element set. %C A358391 This is also the number of order ideals (down-sets) for this lattice. %C A358391 Also similar to the number of antichains in the lattice of set partitions or in the Boolean lattice. %H A358391 Dmitry I. Ignatov, <a href="https://github.com/dimachine/KrewerasNonCrossPartAnti">Supporting iPython code and input files for counting (maximal) antichains of the non-crossing set partition lattice up to n=5</a>, Github repository. %H A358391 G. Kreweras, <a href="https://doi.org/10.1016/0012-365X(72)90041-6">Sur les partitions non croisées d'un cycle</a>, Discrete Math., 4(1972), 333-350. %Y A358391 Cf. A000372 (number of antichains in the Boolean lattice). %Y A358391 Cf. A143673 (number of antichains in the lattice of Dyck paths). %Y A358391 Cf. A302250 (number of antichains in the lattice of set partitions). %K A358391 nonn,hard,more %O A358391 1,1 %A A358391 _Dmitry I. Ignatov_, Nov 13 2022