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A191483
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Even discriminants of imaginary quadratic fields, negated.
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5
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4, 8, 20, 24, 40, 52, 56, 68, 84, 88, 104, 116, 120, 132, 136, 148, 152, 164, 168, 184, 212, 228, 232, 244, 248, 260, 264, 276, 280, 292, 296, 308, 312, 328, 340, 344, 356, 372, 376, 388, 404, 408, 420, 424, 436, 440, 452, 456, 472, 488, 516, 520, 532, 536, 548
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OFFSET
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1,1
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COMMENTS
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LINKS
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FORMULA
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MATHEMATICA
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FundamentalDiscriminantQ[n_Integer] := n != 1 && (Mod[n, 4] == 1 || ! Unequal[ Mod[n, 16], 8, 12]) && SquareFreeQ[n/2^IntegerExponent[n, 2]] (* via Eric E. Weisstein *); -Select[-Range@550, FundamentalDiscriminantQ@# && EvenQ@# &]
(* Second program: *)
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PROG
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(PARI) ok(n)={isfundamental(-n) && n%2==0} \\ Andrew Howroyd, Jul 25 2018
(PARI) ok(n)={n%4==0 && issquarefree(n/4) && n%16<>12} \\ Andrew Howroyd, Jul 25 2018
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CROSSREFS
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KEYWORD
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easy,nonn
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AUTHOR
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STATUS
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approved
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