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Search: id:A007295
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| A007295 |
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Number of elements (a b, c d) in GL(2,Z) with |det| = 1, trace <= n and 0 <= a <= {b, c} <= d. |
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+0
1
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| 1, 2, 4, 8, 11, 18, 22, 30, 36, 48, 53, 67, 74, 87, 100, 120, 125, 145, 155, 179, 193, 215, 227, 255, 273, 303, 317, 339, 356, 404, 416, 444, 463, 506, 525, 567, 592, 624, 647, 707
(list; graph; listen)
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OFFSET
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1,2
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EXAMPLE
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Example from Neven Juric, Apr 21 2008: a(5) = 11 from the matrices (0 1, 1 1), (0 1, 1 2), (0 1, 1 3), (0 1, 1 4), (0 1, 1 5), (1 1, 1 2), (1 1, 2 3), (1 1, 3 4), (1 2, 1 3), (1 2, 2 3), (1 3, 1 4).
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CROSSREFS
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Cf. A006546, A007104, A007203.
Sequence in context: A153195 A010068 A120632 this_sequence A053439 A033956 A159693
Adjacent sequences: A007292 A007293 A007294 this_sequence A007296 A007297 A007298
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KEYWORD
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nonn
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AUTHOR
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John Lewis (frc.mass.edu)
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