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A087785 Number of elements in GL(2,Z_n) x with x^2 == -I mod n where I is the identity matrix. 0
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

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

CROSSREFS

Cf. A066907, A000089.

Sequence in context: A025017 A133427 A027070 * A081198 A275978 A242211

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

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Last modified August 8 19:29 EDT 2020. Contains 336298 sequences. (Running on oeis4.)