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A104888 Class number of binary quadratic forms with radicand A005117(n). 1
1, 2, 1, 2, 2, 2, 2, 1, 2, 4, 1, 2, 2, 2, 2, 2, 1, 4, 2, 2, 4, 4, 1, 2, 4, 1, 4, 2, 2, 2, 4, 1, 4, 2, 2, 2, 1, 2, 2, 4, 2, 2, 4, 2, 1, 2, 2, 4, 6, 4, 2, 2, 2, 4, 1, 4, 2, 2, 4, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET

2,2

COMMENTS

The fundamental discriminant D and the radicand m (which is squarefree) are related via D=m if m=1 (mod 4) and D=4*m if m=2,3 (mod 4).

REFERENCES

Hua Loo Keng, Introduction to Number Theory, Springer-Verlag, 1982, pp. 465-472.

LINKS

Table of n, a(n) for n=2..61.

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, Masters thesis (2001), Appendix B.

CROSSREFS

Cf. A003646, A087048.

Sequence in context: A057768 A317990 A106030 * A286885 A254885 A108461

Adjacent sequences:  A104885 A104886 A104887 * A104889 A104890 A104891

KEYWORD

nonn

AUTHOR

Steven Finch, May 03 2005

STATUS

approved

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Last modified May 23 11:05 EDT 2019. Contains 323513 sequences. (Running on oeis4.)