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A256036
Triangle read by rows: number of idempotents of rank k in Brauer monoid B_n.
0
1, 0, 1, 1, 0, 1, 0, 9, 0, 1, 9, 0, 30, 0, 1, 0, 225, 0, 70, 0, 1, 225, 0, 1575, 0, 135, 0, 1, 0, 11025, 0, 6615, 0, 231, 0, 1, 11025, 0, 132300, 0, 20790, 0, 364, 0, 1, 0, 893025, 0, 873180, 0, 54054, 0, 540, 0, 1, 893025, 0, 16372125, 0, 4054050, 0, 122850, 0, 765, 0, 1
OFFSET
0,8
LINKS
I. Dolinka, J. East, A. Evangelou, D. FitzGerald, N. Ham, et al., Enumeration of idempotents in diagram semigroups and algebras, arXiv preprint arXiv:1408.2021 [math.GR], 2014.
EXAMPLE
Triangle begins:
1
0, 1
1, 0, 1
0, 9, 0, 1
9, 0, 30, 0, 1
0, 225, 0, 70, 0, 1
225, 0, 1575, 0, 135, 0, 1
0, 11025, 0, 6615, 0, 231, 0, 1
11025, 0, 132300, 0, 20790, 0, 364, 0, 1
0, 893025, 0, 873180, 0, 54054, 0, 540, 0, 1
893025, 0, 16372125, 0, 4054050, 0, 122850, 0, 765, 0, 1
...
CROSSREFS
Sequence in context: A118811 A200488 A249418 * A065471 A310000 A199284
KEYWORD
nonn,tabl
AUTHOR
N. J. A. Sloane, Mar 14 2015
STATUS
approved