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%I #26 Jul 20 2018 17:35:42
%S 84,120,132,168,195,228,280,312,340,372,408,435,483,520,532,555,595,
%T 627,708,715,760,795,1012,1435
%N Negated discriminants of imaginary quadratic number fields whose class group is isomorphic to the Klein 4-group, C2 x C2.
%C Added keyword "full" - This sequence is a subsequence of A013658, whose last term is 1555. I have verified that the terms above are complete and correct. - _Rick L. Shepherd_, May 06 2013
%H Alexandre Gélin, Everett W. Howe, and Christophe Ritzenthaler, <a href="https://arxiv.org/abs/1806.03826">Principally Polarized Squares of Elliptic Curves with Field of Moduli Equal To Q</a>, arXiv:1806.03826 [math.NT], 2018 (see table 1 page 4).
%H Rick L. Shepherd, <a href="http://libres.uncg.edu/ir/uncg/f/Shepherd_uncg_0154M_11099.pdf">Binary quadratic forms and genus theory</a>, Master of Arts Thesis, University of North Carolina at Greensboro, 2013.
%o (PARI) ok(n)={isfundamental(-n) && [2, 2] == quadclassunit(-n).cyc} \\ _Andrew Howroyd_, Jul 20 2018
%Y Subsequence of A013658.
%K nonn,fini,full
%O 1,1
%A _David Terr_, Jun 28 2011