A066514 Number of subgroups of the group GL(2,Z_n) of invertible 2 X 2 matrices mod n (sequence A000252).

1, 6, 55, 234, 466, 758, 1704, 24587, 6656, 6718, 6428, 114210, 17158, 26180, 135869, 701426, 33277, 126920, 52320, 1341656, 469872, 87924, 48976, 50257306, 140918, 291060, 348528, 3952920, 175438, 3685062, 285952, 12024029, 1657948, 567994, 4624192, 15262640, 539046, 838096

Offset: 1

Author

Sharon Sela (sharonsela(AT)hotmail.com), Jan 04 2002

Keywords

• nonn

Crossrefs

Cf. A000252.

Programs

GAP

c := CyclicGroup(n); aut := AutomorphismGroup(DirectProduct(c,c)); lat := LatticeSubgroups(aut);

Magma

[&+[s`length : s in Subgroups(GL(2,ResidueClassRing(n)))] : n in [2..10]]; // Robin Visser, Aug 09 2023

Extensions

a(7)-a(11) from Andrew Howroyd, Jul 02 2018

More terms from Robin Visser, Aug 09 2023