A087785 Number of elements in GL(2,Z_n) x with x^2 == -I mod n where I is the identity matrix.

1, 4, 6, 12, 32, 24, 42, 48, 54, 128, 110, 72, 184, 168, 192, 192, 308, 216, 342, 384, 252, 440, 506, 288, 752, 736, 486, 504, 872, 768, 930, 768, 660, 1232, 1344, 648, 1408, 1368, 1104, 1536, 1724, 1008, 1806, 1320, 1728, 2024, 2162, 1152, 2058, 3008, 1848

Offset

1,2

Links

Table of n, a(n) for n=1..51.

Crossrefs

Cf. A066907, A000089.

Sequence in context: A025017 A133427 A027070 * A366772 A081198 A275978

Adjacent sequences: A087782 A087783 A087784 * A087786 A087787 A087788

Keyword

mult,nonn

Author

Yuval Dekel (dekelyuval(AT)hotmail.com), Oct 06 2003

Extensions

More terms from David Wasserman, Jun 17 2005

Status

approved