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Search: id:A006643
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| A006643 |
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Class number of quadratic field with discriminant -4n and n runs through numbers congruent to 1 or 2 mod 4.
(Formerly M0225)
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+0
2
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| 1, 1, 2, 2, 2, 2, 4, 4, 4, 2, 6, 6, 4, 4, 4, 2, 6, 8, 4, 4, 6, 4, 2, 6, 8, 8, 8, 8, 4, 4, 10, 8, 4, 4, 4, 10, 12, 4, 8, 4, 14, 4, 8, 6, 6, 12, 8, 8, 6, 10, 12, 4, 4, 14, 8, 8, 8, 4, 8, 16, 14, 8, 6, 8, 16, 8, 10, 12
(list; graph; listen)
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OFFSET
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1,3
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REFERENCES
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D. A. Buell, Binary Quadratic Forms. Springer-Verlag, NY, 1989, pp. 224-241.
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
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CROSSREFS
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Cf. A006642.
Sequence in context: A085311 A052273 A074912 this_sequence A080217 A157901 A072376
Adjacent sequences: A006640 A006641 A006642 this_sequence A006644 A006645 A006646
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KEYWORD
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nonn,more
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com), Mira Bernstein (mira(AT)math.berkeley.edu)
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