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A028726
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Nonsquares mod 13.
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1
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OFFSET
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1,1
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LINKS
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EXAMPLE
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Since 2 is not a perfect square and there are no solutions to x^2 = 2 mod 13, 2 is in the sequence.
Although 3 is not a perfect square either, there are solutions to x^2 = 3 mod 13, such as x = 4, x = 9. Hence 3 is not in the sequence.
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MATHEMATICA
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Select[Range[0, 12], JacobiSymbol[#, 13] == -1 &] (* Alonso del Arte, Dec 13 2019 *)
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PROG
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(Scala) (0 to 12).diff((1 to 13).map(n => (n * n) % 13)) // Alonso del Arte, Dec 13 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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