A305416 Negated discriminants of imaginary quadratic number fields whose class group is isomorphic to the Klein 8-group, C_2 x C_2 x C_2.

420, 660, 840, 1092, 1155, 1320, 1380, 1428, 1540, 1848, 1995, 3003, 3315

Offset: 1

Author

Vincenzo Librandi, Jun 12 2018

Keywords

• nonn
• fini
• full

Comments

Intersection of A046005 and A003644. Note that A003644 = A014602 union A014603 union A192322 union {a(n)} union {5460}. - Jianing Song, Jul 12 2018

Links

• Alexandre Gélin, Everett W. Howe, and Christophe Ritzenthaler, Principally Polarized Squares of Elliptic Curves with Field of Moduli Equal To Q, arXiv:1806.03826 [math.NT], 2018 (see table 1 page 4).

Crossrefs

Cf. A003644, A014602, A014603, A192322.

Subsequence of A046005 and A003644.

Programs

Mathematica

A046005 = Import["https://oeis.org/A046005/b046005.txt", "Table"][[All, 2]];
A003644 = Import["https://oeis.org/A003644/b003644.txt", "Table"][[All, 2]];
A046005 ~Intersection~ A003644 (* Jean-François Alcover, Sep 25 2019 *)

PARI

ok(n)={isfundamental(-n) && [2, 2, 2] == quadclassunit(-n).cyc} \\ Andrew Howroyd, Jul 20 2018