A003648 Class number of quadratic forms with discriminant 4n, n == 2,3^( mod 4). (Formerly M0210)

1, 2, 2, 2, 2, 2, 2, 4, 2, 2, 2, 2, 4, 2, 4, 4, 2, 4, 4, 2, 2, 2, 4, 4, 2, 2, 2, 4, 2, 4, 2, 2, 4, 6, 4, 2, 2, 4, 4, 2, 4, 4, 2, 2, 2, 4, 4, 4, 4, 2, 4, 2, 4, 2, 4, 2, 2, 4, 2, 6, 4, 4, 2, 4, 4, 2, 4, 2, 2, 2, 4, 4, 4, 2, 4, 4, 4, 4, 4, 2, 4, 8, 2, 2, 4, 2, 8, 2, 2, 4, 2, 8, 4, 6, 8, 2, 4, 8, 12, 4, 2, 4, 4, 2

Offset

2,2

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=2..105.

Crossrefs

Cf. A003647.

Sequence in context: A358473 A369978 A083261 * A003642 A100007 A104369

Adjacent sequences: A003645 A003646 A003647 * A003649 A003650 A003651

Keyword

nonn

Author

N. J. A. Sloane, Mira Bernstein

Status

approved