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%I #16 Mar 04 2020 22:39:14
%S 40,60,65,85,104,105,120,136,140,145,156,165,168,185,204,205,220,221,
%T 229,232,257,264,265,273,280,285,296,305,312,316,321,328,345,348,357,
%U 364,365,377,380,385,401,408,424,429,440,444,445,456,460,465,469,473
%N Discriminants of real quadratic number fields with class number >= 2.
%D H. Cohen, Advanced Topics in Computational Number Theory, Springer, 2000, p. 534.
%D H. Hasse, Number Theory, Springer-Verlag, NY, 1980, p. 576.
%H T. D. Noe, <a href="/A035120/b035120.txt">Table of n, a(n) for n = 1..1000</a>
%H X.-F. Roblot and Igor Schein, <a href="http://euler.univ-lyon1.fr/home/roblot/tables.html#1">Hilbert class field of totally real fields of degree 2, 3 and 4</a>.
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/ClassNumber.html">Class Number</a>
%t Select[Range[500], NumberFieldDiscriminant[Sqrt[#]] == # && NumberFieldClassNumber[Sqrt[#]] >= 2 & ] (* _Jean-François Alcover_, Jul 04 2013 *)
%Y Cf. A003656, A094619.
%K nonn,nice,easy
%O 1,1
%A _N. J. A. Sloane_
%E More terms from Antonio G. Astudillo (afg_astudillo(AT)hotmail.com), May 15 2002
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