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A106031
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a(n) is the number of orbits under the action of GL_2[Z] on the primitive binary quadratic forms of discriminant D, where D<0 is the n-th fundamental discriminant.
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0
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1, 1, 1, 1, 1, 2, 1, 2, 2, 2, 2, 2, 3, 2, 1, 3, 2, 2, 3, 3, 2, 1, 3, 4, 3, 2, 4, 4, 2, 2, 5, 3, 4, 2, 5, 2, 4, 6, 4, 2, 3, 3, 4, 3, 2, 6, 2, 4, 4, 3, 6, 1, 5, 6, 4, 3, 5, 3, 2, 7
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,6
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COMMENTS
| A006641 is the same except it is under the action of SL_2[Z].
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LINKS
| S. R. Finch, Class number theory
Jens Jonasson, Classes of integral binary quadratic forms, Masters thesis (2001), Appendix B.
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EXAMPLE
| D=-3, -4, -7, -8, -11, -15, -19, -20, -23, -24, -31, ...,
that is, A003657 negated.
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CROSSREFS
| Cf. A003657, A006641.
Sequence in context: A064131 A105194 A008335 * A055175 A025819 A110102
Adjacent sequences: A106028 A106029 A106030 * A106032 A106033 A106034
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KEYWORD
| nonn
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AUTHOR
| S. R. Finch (Steven.Finch(AT)inria.fr), May 05 2005
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