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A074385
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Square root of sum of divisors, when it is a square.
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2
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1, 2, 6, 12, 12, 11, 12, 12, 12, 18, 24, 18, 16, 18, 24, 24, 24, 20, 24, 24, 28, 24, 24, 31, 30, 24, 36, 24, 24, 36, 32, 28, 36, 36, 30, 36, 36, 42, 36, 42, 32, 48, 36, 48, 42, 42, 40, 42, 60, 56, 48, 48, 42, 36, 62, 36, 36, 48, 40, 60, 48, 42, 48, 40, 48, 60, 48, 56, 60, 48
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OFFSET
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1,2
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LINKS
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FORMULA
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MATHEMATICA
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Select[Sqrt[DivisorSigma[1, Range@1800]], IntegerQ] (* Ivan Neretin, Jun 05 2015 *)
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PROG
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(PARI) lista(nn) = {for (n=1, nn, if (issquare(s=sigma(n)), print1(sqrtint(s), ", ")); ); } \\ Michel Marcus, Dec 18 2013
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CROSSREFS
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KEYWORD
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AUTHOR
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STATUS
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approved
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