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A378072
Number of elements in the completion of the Bruhat order on B_n.
0
1, 2, 10, 132, 4824, 493600
OFFSET
0,2
COMMENTS
Lascoux and Schützenberger have shown that the completion of type B Bruhat order is distributive, and have described its irreducible elements. It follows that a(n) is the number of antichains in the poset of irreducible elements of the Bruhat order on B_n.
This sequence is a type B analog of A005130, since ASMs form a lattice isomorphic to the completion of type A Bruhat order.
LINKS
A. Lascoux and M.-P. Schützenberger, Treillis et bases des groupes de Coxeter, Electron. J. Combin. 3 (1996), #R27.
CROSSREFS
Cf. A005130 (ASMs), A005158 (centrally symmetric ASMs), A000165 (number of elements in B_n).
Sequence in context: A254431 A011838 A355463 * A336537 A118183 A134051
KEYWORD
nonn,more
AUTHOR
Ludovic Schwob, Nov 16 2024
STATUS
approved