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Number of normal subgroups of the group of n X n signed permutations matrices (described in sequence A066051).
0

%I #6 Sep 22 2013 06:24:09

%S 2,6,9,11,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,

%T 9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,

%U 9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9

%N Number of normal subgroups of the group of n X n signed permutations matrices (described in sequence A066051).

%C The similar sequence for the "ordinary" symmetric group S_n is 1, 2, 3, 4, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, ...

%F For n>=5 a(n) = 9.

%Y Cf. A066051.

%K nonn

%O 1,1

%A Sharon Sela (sharonsela(AT)hotmail.com), Jan 07 2002