A051998 Consider real quadratic fields of ERD-type with class groups of exponent 2 and discriminants of the form D = r^2*k^2+4k, k odd; sequence gives values of k.

1, -15, -5, -17, -19, -21, 1, -3, 1, 1, 5, 3, -33, 1, -35, -5, 5, -39, -13, -41, 3, 1, 1, -15, -3, 3, 5, 15, -7, -51, 1, 3, -55, 1, -5, 5, -3, 1, -21, -65, 5, 13, -69, 3, -15, 5, -11, 7, 3, -17, 17, -89, 29, -91, 13, -95, -5, 33, 1, -15, 35, 39, 11, 5, 1, 3, 19, 5, -11, 5, -51, 5, 53, -165, -7, -3, 1, 21, -29, -5, 21

Offset: 1

Author

N. J. A. Sloane, Jan 04 2000

Keywords

• sign
• fini
• full

Comments

Excludes discriminants appearing in A051990.

References

• R. A. Mollin, Quadratics, CRC Press, 1996, Appendix A, Table A4(3), column k.

Crossrefs

Cf. A051990, A051991, A051992, A051993, A051994, A051995, A051996, A051997.

Extensions

a(69) and following from Georg Fischer, Sep 21 2021