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A114082
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sigma(n) plus the n-th prime gives a square.
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3
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3, 6, 7, 9, 18, 58, 73, 134, 198, 251, 278, 287, 461, 483, 505, 525, 529, 665, 772, 939, 960, 986, 1291, 1432, 1463, 1629, 2115, 2931, 2991, 3422, 3888, 4159, 4231, 4548, 4715, 6256, 7867, 9148, 9474, 9540, 9958, 10535, 12035, 12081, 12223, 12511
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OFFSET
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1,1
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LINKS
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EXAMPLE
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sigma(2115)+p(2115)=22201=149^2.
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MATHEMATICA
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n=0; p=1; seq={}; Do[p = NextPrime[p]; n++; If[IntegerQ @ Sqrt [p + DivisorSigma[1, n]], AppendTo[seq, n]], {10^4}]; seq (* Amiram Eldar, Aug 18 2019 *)
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PROG
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(PARI) isok(n) = issquare(sigma(n) + prime(n)); \\ Michel Marcus, Jan 11 2014
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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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