A185349 - OEIS

%I #11 Oct 25 2012 11:44:09

%S 1,1,2,6,22,93

%N Number of isomorphism classes of partially ordered sets of length n that occur as intervals in weak Bruhat order of some Coxeter group.

%D Björner, Anders; Brenti, Francesco. Combinatorics of Coxeter groups. Graduate Texts in Mathematics, 231. Springer, New York, 2005.

%H Matthew J. Samuel, <a href="http://arxiv.org/abs/1101.4655">Word posets, complexity, and Coxeter groups</a>, arXiv:1101.4655 [math.CO]

%H Matthew J. Samuel, <a href="http://www.math.rutgers.edu/~msamuel/enumweak.pdf">Enumeration of small weak order intervals</a>

%Y a(n) >= A000112(n).

%K nonn,hard,more

%O 0,3

%A _Matthew J. Samuel_, Feb 15 2011