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A229296
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Number of solutions to x^2 + y^2 == n (mod 2*n) for x,y in [0, 2*n).
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4
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2, 4, 2, 8, 18, 4, 2, 16, 18, 36, 2, 8, 50, 4, 18, 32, 66, 36, 2, 72, 2, 4, 2, 16, 130, 100, 18, 8, 114, 36, 2, 64, 2, 132, 18, 72, 146, 4, 50, 144, 162, 4, 2, 8, 162, 4, 2, 32, 98, 260, 66, 200, 210, 36, 18, 16, 2, 228, 2, 72, 242, 4, 18, 128, 450, 4, 2
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OFFSET
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1,1
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LINKS
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FORMULA
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MATHEMATICA
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A[n_] := Sum[If[Mod[a^2+b^2, 2n] == n, 1, 0], {a, 0, 2n - 1}, {b, 0, 2n - 1}]; Array[A, 100]
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PROG
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(PARI) a(n)={my(m=2*n); my(p=Mod(sum(i=0, m-1, x^(i^2%m)), x^m-1)^2); polcoeff( lift(p), n)} \\ Andrew Howroyd, Aug 07 2018
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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