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A006374
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Number of reduced binary quadratic forms of determinant n.
(Formerly M0214)
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4
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1, 1, 2, 2, 2, 2, 2, 3, 3, 2, 4, 4, 2, 4, 4, 4, 4, 3, 4, 6, 4, 2, 6, 6, 3, 6, 6, 4, 6, 4, 6, 7, 4, 4, 8, 8, 2, 6, 8, 6, 8, 4, 4, 10, 6, 4, 10, 8, 5, 7, 8, 6, 6, 8, 8, 12, 4, 2, 12, 8, 6, 8, 10, 8, 8, 8, 4, 12, 8, 4, 14, 9, 4, 10, 10, 10, 8, 4, 10, 14, 9, 4, 12, 12, 4, 10, 12, 6, 12, 10, 8
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,3
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REFERENCES
| J. H. Conway and N. J. A. Sloane, "Sphere Packings, Lattices and Groups", Springer-Verlag, p. 360.
A. Hurwitz and N. Kritikos, transl. with add. material by W . C. Schulz, "Lectures on Number Theory", Springer-Verlag, New York, 1986, p. 186.
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
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CROSSREFS
| Cf. A006371, A006375, A096446, A096445.
Sequence in context: A067752 A025422 A078640 * A193677 A137921 A064876
Adjacent sequences: A006371 A006372 A006373 * A006375 A006376 A006377
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KEYWORD
| nonn,nice,easy
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com).
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