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A106030
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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=m if m=1 (mod 4), D=4*m otherwise and m>1 is the n-th squarefree number.
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0
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1, 2, 1, 2, 2, 2, 2, 1, 2, 4, 1, 2, 2, 2, 2, 2, 1, 4, 2, 2, 3, 4, 1, 2, 4, 1, 4, 2, 2, 2, 4, 1, 4, 2, 2, 2, 1, 2, 2, 4, 2, 2, 4, 2, 1, 2, 2, 4, 4, 3, 2, 2, 2, 4, 1, 4, 2, 2, 4, 1
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| A104888 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
| m=2, 3, 5, 6, 7, 10, 11, 13, 14, 15, 17, ...
with corresponding discriminant
D=8, 12, 5, 24, 28, 40, 44, 13, 56, 60, 17, ....
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CROSSREFS
| Cf. A104888.
Sequence in context: A073810 A055255 A057768 * A104888 A108461 A026535
Adjacent sequences: A106027 A106028 A106029 * A106031 A106032 A106033
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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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