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A188539
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Numbers n such that n^2 plus number of divisors of n^2 is prime.
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2
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1, 2, 8, 10, 36, 38, 40, 44, 52, 58, 62, 68, 76, 80, 82, 98, 104, 108, 118, 124, 130, 136, 142, 154, 160, 170, 172, 182, 202, 208, 212, 218, 236, 238, 242, 266, 284, 290, 298, 316, 338, 356, 358, 364, 376, 382, 388, 410
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OFFSET
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1,2
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COMMENTS
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LINKS
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MAPLE
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select(n -> isprime(n^2 + numtheory:-tau(n^2)), [1, seq(i, i=2..1000, 2)]); # Robert Israel, Apr 11 2018
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MATHEMATICA
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Select[Range[500], PrimeQ[#^2 + DivisorSigma[0, #^2]] &] (* Alonso del Arte, Apr 08 2011 *)
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PROG
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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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