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A225606
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Number of distinct lines passing through 3 or more points in an n X n grid.
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4
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0, 0, 0, 8, 14, 32, 58, 108, 174, 296, 406, 628, 898, 1216, 1582, 2188, 2754, 3528, 4398, 5524, 6778, 8336, 9778, 11812, 14038, 16456, 19066, 22540, 25954, 29968, 34270, 39116, 44282, 50312, 56026, 63196, 70798, 78984
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OFFSET
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0,4
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LINKS
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FORMULA
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MATHEMATICA
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f[n_, k_] := Sum[x = kx/k; y = ky/k; If[IntegerQ[x] && IntegerQ[y] && CoprimeQ[x, y], (n - Abs[kx])(n - Abs[ky]), 0], {kx, -n + 1, n - 1}, {ky, -n + 1, n - 1}];
a[n_] := (f[n, 2] - f[n, 3])/2;
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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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