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 A051996 Consider real quadratic fields of ERD-type with class groups of exponent 2 and discriminants of the form D = r^2*k^2+k, k odd; sequence gives values of k. 8
 1, -1, 1, 5, -1, 3, -7, 1, -3, -5, 5, -11, 1, -1, 1, 13, -1, 7, -15, -3, 5, -1, 1, 3, 1, -5, 21, -1, 1, 1, -13, -15, 3, 15, -31, 1, -1, 1, 17, -35, -7, 5, -1, 1, 19, -39, -3, -5, 5, 41, 3, 5, -23, 1, 1, -3, 17, 13, -1, -19, -29, 1, -3, 5, -31, 21, 33, -3, -7, 35, 3, 1, -15, -19, -39, 5, 41, -21, -11, 11, 5, 1, 5, -55, 55, 29, 5, -11, 1, -35, 35, 1, -7, -3, 1, 1, -15, 21 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,4 REFERENCES R. A. Mollin, Quadratics, CRC Press, 1996, Appendix A, Table A4(1), column k. LINKS Table of n, a(n) for n=1..98. CROSSREFS Cf. A051990, A051991, A051992, A051993, A051994, A051995, A051997, A051998. Sequence in context: A174879 A327965 A094136 * A242303 A214803 A225984 Adjacent sequences: A051993 A051994 A051995 * A051997 A051998 A051999 KEYWORD sign,fini,full AUTHOR N. J. A. Sloane, Jan 04 2000 EXTENSIONS a(73) and following from Georg Fischer, Sep 21 2021 STATUS approved

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Last modified July 25 04:49 EDT 2024. Contains 374586 sequences. (Running on oeis4.)