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A206449
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Values of sigma(p) of primes p such that sigma(p) = sigma(c) has solution for some composite number c.
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0
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12, 18, 24, 32, 42, 48, 54, 60, 72, 80, 84, 90, 98, 104, 108, 114, 128, 132, 140, 152, 168, 180, 182, 192, 224, 228, 234, 240, 252, 264, 270, 272, 294, 308, 312, 360, 384, 390, 420, 432, 434, 440, 444, 450, 468, 480, 492, 504, 522, 558, 570, 572, 588, 594, 600
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OFFSET
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1,1
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COMMENTS
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Corresponding values of sigma(p) of primes p from A158913.
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LINKS
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FORMULA
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MATHEMATICA
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Union@ Select[ DivisorSigma[1, Select[ Range@ 100, !PrimeQ@# &]], PrimeQ[# - 1] &] (* Robert G. Wilson v, Feb 09 2012 *)
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CROSSREFS
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Cf. A158913 (primes p such that there is a composite c with sigma(p)=sigma(c)), A206448 (values of sigma(c) of composite numbers c such that sigma(c) = sigma(d) has solution for any other composite number d), A000203.
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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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