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A006642
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Class number of quadratic field with discriminant -4n+1.
(Formerly M0152)
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1
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1, 1, 1, 2, 1, 3, 3, 2, 4, 1, 5, 2, 4, 3, 1, 7, 5, 3, 6, 2, 8, 5, 3, 8, 2, 10, 2, 5, 5, 3, 10, 7, 4, 10, 1, 11, 5, 8, 2, 13, 4, 9, 4, 3, 14, 4, 7, 5, 12, 2, 15, 6, 7, 12, 4, 13, 2, 11, 3, 14, 4, 8, 8, 10, 3, 19, 10, 4
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,4
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REFERENCES
| 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
| Cf. A006643.
Sequence in context: A128133 A032434 A002347 * A094435 A133341 A111492
Adjacent sequences: A006639 A006640 A006641 * A006643 A006644 A006645
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KEYWORD
| nonn
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com), Mira Bernstein (mira(AT)math.berkeley.edu)
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