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%I #9 Jul 05 2018 02:09:15
%S 1,3,5,12,6,17,8,46,14,22,8,82,12,28,38,112,10,48,12,116,48,28,8,386,
%T 18,44,27,140,12,162,16,232,48,38,64,234,18,42,76,596,16,196,16,140,
%U 108,28,8,1022,24,66,66,232,12,93,64,680,72,44,8,1032,24,56,204
%N Number of normal subgroups of the group GL(2,Z_n) of invertible 2 X 2 matrices mod n (sequence A000252).
%H Andrew Howroyd, <a href="/A066541/b066541.txt">Table of n, a(n) for n = 1..100</a>
%o (GAP) Concatenation([1], List([2..20], n->Size(NormalSubgroups(GL(2, Integers mod n))))); # _Andrew Howroyd_, Jul 04 2018
%Y Cf. A000252, A066514, A316498.
%K nonn
%O 1,2
%A Sharon Sela (sharonsela(AT)hotmail.com), Jan 07 2002
%E Terms a(16) and beyond from _Andrew Howroyd_, Jul 04 2018
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