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A074388
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Numbers of the form 2*k^2 such that sigma(2*k^2) is an odd square.
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1
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195938, 224450, 13645088, 15870978, 18180450, 29184800, 1105252128, 2363968800, 2686005218, 2917410498, 3564550178, 5056357922, 8442721568, 10814792450, 18587462432, 21292224800, 48666384162, 140836104992, 212352534818, 217566422658, 288728564418, 315325993248
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OFFSET
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1,1
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COMMENTS
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No terms whose sum of divisors is a square of a prime below 10^12 were found.
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LINKS
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FORMULA
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EXAMPLE
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195938 = 2*313^2 and sigma(195938) = 294849 = 543^2.
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MATHEMATICA
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Do[s=DivisorSigma[1, 2*(n^2)]; If[IntegerQ[Sqrt[s]]&&Mod[s, 2]==1, Print[2*(n^2)]], {n, 1, 10000000}]
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CROSSREFS
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KEYWORD
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nonn,changed
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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