%I #2 Jun 29 2008 03:00:00
%S 1,2,19,8368,360350697981
%N Number of lattice congruences of the weak order on the Coxeter group B_n.
%C For n=0,1,2,3,4, we have a(n+1) ~ [a(n)]^3 as a very rough order-of-magnitude approximation.
%H N. Reading, <a href="http://arXiv.org/abs/math.CO/0401404">Lattice congruences of the weak order</a>.
%Y Cf. A091687.
%K hard,more,nonn
%O 0,2
%A Nathan Reading (nreading(AT)umich.edu), Jan 28 2004