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A185349
Number of isomorphism classes of partially ordered sets of length n that occur as intervals in weak Bruhat order of some Coxeter group.
0
1, 1, 2, 6, 22, 93
OFFSET
0,3
REFERENCES
Björner, Anders; Brenti, Francesco. Combinatorics of Coxeter groups. Graduate Texts in Mathematics, 231. Springer, New York, 2005.
LINKS
CROSSREFS
a(n) >= A000112(n).
Sequence in context: A091768 A229741 A261518 * A317652 A374544 A374545
KEYWORD
nonn,hard,more
AUTHOR
Matthew J. Samuel, Feb 15 2011
STATUS
approved