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A133676
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Negative discriminants with form class group of exponent 4 (negated).
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4
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39, 55, 56, 63, 68, 80, 128, 136, 144, 155, 156, 171, 184, 196, 203, 208, 219, 220, 224, 252, 256, 259, 260, 264, 275, 276, 291, 292, 308, 320, 323, 328, 336, 355, 360, 363, 384, 387, 388, 400, 456, 468, 475, 504, 507, 528, 544, 552, 564, 568, 576, 580, 592
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OFFSET
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1,1
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COMMENTS
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The sequence is finite. It appears to have exactly 485 terms, the largest being 887040.
The finiteness of the sequence was proved by Earnest and Estes.
I found the 485 terms with PARI and didn't find any other up to 50000000.
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LINKS
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PROG
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(PARI) a(n) = if(n%4==0 || n%4==3, my(v = quadclassunit(-n)[2]); (#v > 0) && (v[1] == 4), 0) \\ Jianing Song, Sep 24 2022
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CROSSREFS
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KEYWORD
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nonn,fini
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AUTHOR
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STATUS
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approved
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