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A013658 Discriminants of imaginary quadratic fields with class number 4 (negated). 26
39, 55, 56, 68, 84, 120, 132, 136, 155, 168, 184, 195, 203, 219, 228, 259, 280, 291, 292, 312, 323, 328, 340, 355, 372, 388, 408, 435, 483, 520, 532, 555, 568, 595, 627, 667, 708, 715, 723, 760, 763, 772, 795, 955, 1003, 1012, 1027, 1227, 1243 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

REFERENCES

H. Cohen, Course in Computational Alg. No. Theory, Springer, 1993, p. 229.

Sung Sik Woo, Cubic formula and cubic curves, Commun. Korean Math. Soc. 28 (2013), No. 2, pp. 209-224; http://dx.doi.org/10.4134/CKMS.2013.28.2.209; http://www.mathnet.or.kr/mathnet/thesis_file/CKMS-28-2-209-224.pdf

LINKS

Giovanni Resta, Table of n, a(n) for n = 1..54 (full sequence, from Weisstein's World of Mathematics)

Rick L. Shepherd, Binary quadratic forms and genus theory, Master of Arts Thesis, University of North Carolina at Greensboro, 2013.

Eric Weisstein's World of Mathematics, Class Number

Index entries for sequences related to quadratic fields

MATHEMATICA

Union[(-NumberFieldDiscriminant[Sqrt[-#]] &) /@ Select[Range[1250], NumberFieldClassNumber[Sqrt[-#]] == 4 &]] (* Jean-Fran├žois Alcover, Jun 27 2012 *)

CROSSREFS

Sequence in context: A252720 A070145 A133676 * A227735 A165346 A268083

Adjacent sequences:  A013655 A013656 A013657 * A013659 A013660 A013661

KEYWORD

nonn,fini,full

AUTHOR

Eric Rains (rains(AT)caltech.edu)

STATUS

approved

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Last modified February 22 09:44 EST 2018. Contains 299449 sequences. (Running on oeis4.)