OFFSET
1,1
COMMENTS
This is also the number of order ideals (down-sets) for this lattice.
Also similar to the number of antichains in the lattice of set partitions or in the Boolean lattice.
LINKS
Dmitry I. Ignatov, Supporting iPython code and input files for counting (maximal) antichains of the non-crossing set partition lattice up to n=5, Github repository.
G. Kreweras, Sur les partitions non croisées d'un cycle, Discrete Math., 4(1972), 333-350.
CROSSREFS
KEYWORD
nonn,hard,more
AUTHOR
Dmitry I. Ignatov, Nov 13 2022
STATUS
approved