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A003638 Number of classes per genus in quadratic field with discriminant -4n, -n == 2,3( mod 4).
(Formerly M0191)
1
1, 1, 1, 1, 1, 1, 2, 2, 1, 1, 3, 3, 1, 1, 2, 1, 3, 4, 1, 2, 3, 1, 1, 3, 4, 2, 2, 2, 1, 2, 5, 2, 1, 2, 1, 5, 6, 1, 4, 2, 7, 1, 1, 3, 3, 3, 4, 2, 3, 5, 3, 1, 1, 7, 4, 2, 2, 2, 2, 8, 7, 2, 3, 4, 4, 1, 5, 3, 7, 3, 1, 4, 5, 3, 4 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,7

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).

LINKS

Table of n, a(n) for n=1..75.

CROSSREFS

Cf. A003637.

Sequence in context: A198380 A152805 A064894 * A094267 A136480 A050603

Adjacent sequences:  A003635 A003636 A003637 * A003639 A003640 A003641

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, Mira Bernstein

STATUS

approved

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Last modified February 16 16:00 EST 2020. Contains 331961 sequences. (Running on oeis4.)