

A106031


a(n) is the number of orbits under the action of GL_2[Z] on the primitive binary quadratic forms of discriminant D, where D < 0 is the nth fundamental discriminant.


0



1, 1, 1, 1, 1, 2, 1, 2, 2, 2, 2, 2, 3, 2, 1, 3, 2, 2, 3, 3, 2, 1, 3, 4, 3, 2, 4, 4, 2, 2, 5, 3, 4, 2, 5, 2, 4, 6, 4, 2, 3, 3, 4, 3, 2, 6, 2, 4, 4, 3, 6, 1, 5, 6, 4, 3, 5, 3, 2, 7
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OFFSET

1,6


COMMENTS

A006641 is the same except it is under the action of SL_2[Z].


LINKS

Table of n, a(n) for n=1..60.
S. R. Finch, Class number theory
Steven R. Finch, Class number theory [Cached copy, with permission of the author]
Jens Jonasson, Classes of integral binary quadratic forms, Master's thesis (2001), Appendix B.


EXAMPLE

D = 3, 4, 7, 8, 11, 15, 19, 20, 23, 24, 31, ...,
that is, A003657 negated.


CROSSREFS

Cf. A003657, A006641.
Sequence in context: A323015 A105194 A008335 * A055175 A339930 A307707
Adjacent sequences: A106028 A106029 A106030 * A106032 A106033 A106034


KEYWORD

nonn


AUTHOR

Steven Finch, May 05 2005


STATUS

approved



