A003639 Number of classes per genus in Q(sqrt -n), n squarefree.

1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 2, 1, 1, 1, 3, 3, 3, 1, 3, 1, 2, 1, 1, 3, 2, 4, 1, 1, 2, 5, 1, 3, 2, 1, 1, 3, 3, 4, 2, 2, 1, 2, 1, 7, 2, 5, 2, 1, 5, 2, 3, 1, 5, 3, 6, 1, 1, 4, 4, 2, 7, 1, 5, 1, 3, 3, 3, 3, 4, 4, 2, 1, 3, 5, 5, 1, 5, 3, 1, 5, 1, 7, 4, 2, 3, 2, 2, 5, 2, 8, 7, 7, 2, 2, 3, 4, 5, 4, 1, 1, 5, 11, 3

Offset: 1

Author

N. J. A. Sloane, Mira Bernstein

Keywords

• nonn

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).