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A007104 Number of elements (a b, c d) in GL(2,Z) with det = -1, trace n and 0 <= a <= {b, c} <= d. 3
1, 1, 1, 2, 1, 4, 1, 4, 4, 4, 2, 10, 1, 5, 7, 12, 1, 10, 4, 10, 12, 4, 6, 24, 4, 12, 7, 10, 5, 26, 6, 20, 13, 12, 7, 30, 11, 4, 15, 32, 6, 26, 6, 28, 23, 12, 7, 52, 12, 10, 28, 10, 6, 40, 14, 44, 17, 24, 12, 56, 19, 12, 20, 36, 27, 44, 11, 28, 16 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

LINKS

Sean A. Irvine, Table of n, a(n) for n = 1..250

CROSSREFS

Sequence in context: A051953 A079277 A066452 * A102627 A296560 A284652

Adjacent sequences:  A007101 A007102 A007103 * A007105 A007106 A007107

KEYWORD

nonn

AUTHOR

John Lewis (frc.mass.edu)

EXTENSIONS

More terms from Sean A. Irvine, Oct 12 2017

STATUS

approved

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Last modified September 21 07:08 EDT 2019. Contains 327253 sequences. (Running on oeis4.)