A051995 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 r.

9, 1, 3, 1, 1, 1, 19, 7, 23, 25, 5, 9, 1, 31, 1, 7, 7, 1, 3, 1, 13, 41, 43, 3, 15, 15, 9, 3, 7, 1, 49, 17, 1, 53, 11, 11, 19, 59, 3, 1, 13, 4, 1, 23, 5, 15, 7, 11, 27, 5, 5, 1, 3, 1, 7, 1, 19, 3, 101, 7, 3, 3, 11, 25, 127, 43, 7, 27, 13, 29, 3, 31, 3, 1, 25, 59, 179, 9, 7, 47, 13

Offset

1,1

Comments

Excludes discriminants appearing in A051990.

References

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

Links

Table of n, a(n) for n=1..81.

Crossrefs

Cf. A051990, A051991, A051992, A051993, A051994, A051996, A051997, A051998.

Sequence in context: A080504 A327958 A154490 * A198835 A010167 A154181

Adjacent sequences: A051992 A051993 A051994 * A051996 A051997 A051998

Keyword

nonn,fini,full

Author

N. J. A. Sloane, Jan 04 2000

Extensions

Offset changed to 1 by Georg Fischer, Sep 21 2021

Status

approved