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A173636
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Number of positive solutions of equation x(x+n)=y*y.
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0
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0, 0, 0, 1, 0, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 4, 2, 1, 2, 1, 1, 4, 1, 1, 4, 2, 1, 3, 1, 1, 4, 1, 3, 4, 1, 4, 2, 1, 1, 4, 4, 1, 4, 1, 1, 7, 1, 1, 7, 2, 2, 4, 1, 1, 3, 4, 4, 4, 1, 1, 4, 1, 1, 7, 4, 4, 4, 1, 1, 4, 4, 1, 7, 1, 1, 7, 1, 4, 4
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OFFSET
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0,10
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COMMENTS
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The solution x=y=0 is not counted.
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LINKS
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FORMULA
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EXAMPLE
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a(9)=2 since x(x+9)=y*y has 2 solutions: x=3, y=6 and x=16, y=20.
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MATHEMATICA
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Join[{0}, Table[Length[{ToRules[Reduce[x (x + n) == y^2 && x > 0 && y > 0, {x, y}, Integers]]}], {n, 100}]]
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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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