%I
%S 420,660,840,1092,1155,1320,1380,1428,1540,1848,1995,3003,3315
%N Negated discriminants of imaginary quadratic number fields whose class group is isomorphic to the Klein 8group, C_2 x C_2 x C_2.
%C Intersection of A046005 and A003644. Note that A003644 = A014602 union A014603 union A192322 union {a(n)} union {5460}.  _Jianing Song_, Jul 12 2018
%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).
%t A046005 = Import["https://oeis.org/A046005/b046005.txt", "Table"][[All, 2]];
%t A003644 = Import["https://oeis.org/A003644/b003644.txt", "Table"][[All, 2]];
%t A046005 ~Intersection~ A003644 (* _JeanFrançois Alcover_, Sep 25 2019 *)
%o (PARI) ok(n)={isfundamental(n) && [2, 2, 2] == quadclassunit(n).cyc} \\ _Andrew Howroyd_, Jul 20 2018
%Y Cf. A003644, A014602, A014603, A192322.
%Y Subsequence of A046005 and A003644.
%K nonn,fini,full
%O 1,1
%A _Vincenzo Librandi_, Jun 12 2018
