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A035120 Discriminants of real quadratic number fields with class number >= 2. 7
40, 60, 65, 85, 104, 105, 120, 136, 140, 145, 156, 165, 168, 185, 204, 205, 220, 221, 229, 232, 257, 264, 265, 273, 280, 285, 296, 305, 312, 316, 321, 328, 345, 348, 357, 364, 365, 377, 380, 385, 401, 408, 424, 429, 440, 444, 445, 456, 460, 465, 469, 473 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

REFERENCES

H. Cohen, Advanced Topics in Computational Number Theory, Springer, 2000, p. 534.

H. Hasse, Number Theory, Springer-Verlag, NY, 1980, p. 576.

LINKS

T. D. Noe, Table of n, a(n) for n=1..1000

X.-F. Roblot and Igor Schein, Hilbert class field of totally real fields of degree 2, 3 and 4.

Eric Weisstein's World of Mathematics, Class Number

MATHEMATICA

Select[Range[500], NumberFieldDiscriminant[Sqrt[#]] == # && NumberFieldClassNumber[Sqrt[#]] >= 2 & ] (* Jean-Fran├žois Alcover, Jul 04 2013 *)

CROSSREFS

Cf. A003656, A094619.

Sequence in context: A100333 A116309 A126816 * A094619 A052475 A182205

Adjacent sequences:  A035117 A035118 A035119 * A035121 A035122 A035123

KEYWORD

nonn,nice,easy

AUTHOR

N. J. A. Sloane.

EXTENSIONS

More terms from Antonio G. Astudillo (afg_astudillo(AT)hotmail.com), May 15 2002

STATUS

approved

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Last modified July 31 05:26 EDT 2014. Contains 245079 sequences.