A322710 Negative discriminants with form class number 2 (negated).

15, 20, 24, 32, 35, 36, 40, 48, 51, 52, 60, 64, 72, 75, 88, 91, 99, 100, 112, 115, 123, 147, 148, 187, 232, 235, 267, 403, 427

Offset: 1

Author

Jianing Song, Dec 24 2018

Keywords

• nonn
• fini
• full

Comments

This is the full sequence.

The j-invariants for these discriminants are quadratic integers. See the links below for a full list.

Links

• Rick L. Shepherd, Binary quadratic forms and genus theory, Master of Arts Thesis, University of North Carolina at Greensboro, 2013
• Jianing Song, j-invariants for the discriminants with form class number 2 and their Hilbert class polynomials
• Eric Weisstein's World of Mathematics, Class Number

Crossrefs

Cf. A014603, A305474.

Cf. A133675 (negative discriminants with form class group isomorphic to the trivial group), this sequence (isomorphic to C_2), A328825 (isomorphic to C_3), A329182 (isomorphic to C_2 X C_2), A330219 (isomorphic to C_4).

Programs

PARI

for(n=1, 500, if((-n)%4<=1&&quadclassunit(-n)[1]==2, print1(n, ", ")))