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Number of ramified partitions (I,J) of size n, where J is balanced with respect to up brackets and down brackets.
1

%I #35 Apr 05 2024 00:50:29

%S 1,1,5,48,747,17040,531810,21634515,1107593235,69482175840,

%T 5229801016650,464302838867175,47939015445032250,5688437019459319125,

%U 767922887039461928775,116915022542869964287875,19922514312608630279431875,3774243527942494591068084000,790220453914362566924533955250

%N Number of ramified partitions (I,J) of size n, where J is balanced with respect to up brackets and down brackets.

%C a(n) is the cardinality of the balanced ramified Brauer monoid bBr_n.

%H Diego Arcis, <a href="/A370758/b370758.txt">Table of n, a(n) for n = 0..200</a>

%H Francesca Aicardi, Diego Arcis, and Jesús Juyumaya, <a href="https://arxiv.org/abs/2107.04170">Brauer and Jones tied monoids</a>, arXiv:2107.04170 [math.RT], 2021.

%H Francesca Aicardi, Diego Arcis, and Jesús Juyumaya, <a href="https://doi.org/10.1016/j.jpaa.2022.107161">Brauer and Jones tied monoids</a>, J. Pure. Appl. Algebra 227 (2023), 107161.

%F a(n) = Sum_{k=0..n/2} n!^2/(2^(2*k)*k!^2*(n-2*k)!) * A343254(n,k).

%e a(3) = 48 is the number of ramified partitions (I,J) of size 3, in which each block of J contains the same number of up brackets and down brackets from I, i.e., each block of J contains either no brackets from I or one up and one down bracket from I.

%Y Cf. A343254.

%K nonn

%O 0,3

%A _Diego Arcis_, Feb 29 2024