

A033266


Numbers n such that every genus of binary quadratic forms of discriminant 4n consists of a single class and the class number h(4n) = 2.


4



5, 6, 8, 9, 10, 12, 13, 15, 16, 18, 22, 25, 28, 37, 58
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OFFSET

1,1


REFERENCES

David A. Cox, "Primes of the Form x^2 + n y^2", Wiley, 1989, p. 60.
G. B. Mathews, Theory of Numbers, Chelsea, no date, p. 263.


LINKS

Table of n, a(n) for n=1..15.


PROG

(PARI) ok(n)={my(u=quadclassunit(4*n).cyc); #u==1 && !select(t>t<>2, u)} \\ Andrew Howroyd, Jun 09 2018


CROSSREFS

A subsequence of A000926.
Cf. A033267, A033268, A033269.
Sequence in context: A242290 A296562 A057854 * A102408 A240564 A189719
Adjacent sequences: A033263 A033264 A033265 * A033267 A033268 A033269


KEYWORD

nonn,fini,full


AUTHOR

N. J. A. Sloane


STATUS

approved



