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A046006
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Discriminants of imaginary quadratic fields with class number 9 (negated).
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8
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199, 367, 419, 491, 563, 823, 1087, 1187, 1291, 1423, 1579, 2003, 2803, 3163, 3259, 3307, 3547, 3643, 4027, 4243, 4363, 4483, 4723, 4987, 5443, 6043, 6427, 6763, 6883, 7723, 8563, 8803, 9067, 10627
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OFFSET
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1,1
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COMMENTS
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The class group of Q[sqrt(-4027)] is isomorphic to C_3 X C_3. For all other d in this sequence, the class group of Q[sqrt(-d)] is isomorphic to C_9. - Jianing Song, Dec 01 2019
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LINKS
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MATHEMATICA
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Union[(-NumberFieldDiscriminant[Sqrt[-#]] &) /@ Select[Range[10700], NumberFieldClassNumber[Sqrt[-#]] == 9 &]] (* Jean-François Alcover, Jun 27 2012 *)
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PROG
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(PARI)
ok(n)={isfundamental(-n) && quadclassunit(-n).no == 9};
for(n=1, 11000, if(ok(n)==1, print1(n, ", "))) \\ G. C. Greubel, Mar 01 2019
(Sage)
[n for n in (1..4000) if is_fundamental_discriminant(-n) and QuadraticField(-n, 'a').class_number()==9] # G. C. Greubel, Mar 01 2019
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CROSSREFS
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KEYWORD
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nonn,fini,full
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AUTHOR
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STATUS
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approved
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