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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. 8
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 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
COMMENTS
Excludes discriminants appearing in A051990.
REFERENCES
R. A. Mollin, Quadratics, CRC Press, 1996, Appendix A, Table A4(3), column k.
LINKS
CROSSREFS
Sequence in context: A196187 A004480 A114332 * A131611 A166209 A040215
KEYWORD
sign,fini,full
AUTHOR
N. J. A. Sloane, Jan 04 2000
EXTENSIONS
a(69) and following from Georg Fischer, Sep 21 2021
STATUS
approved

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Last modified July 12 16:00 EDT 2024. Contains 374251 sequences. (Running on oeis4.)