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A066653
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Squarefree numbers k such that the pair 2*k +- 1 is a twin prime pair.
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4
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2, 3, 6, 15, 21, 30, 51, 69, 114, 141, 174, 210, 231, 285, 309, 321, 330, 411, 429, 510, 546, 615, 645, 651, 714, 741, 834, 849, 861, 894, 939, 966, 1041, 1065, 1119, 1155, 1191, 1329, 1365, 1401, 1626, 1686, 1695, 1731, 1770
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OFFSET
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1,1
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LINKS
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FORMULA
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EXAMPLE
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MATHEMATICA
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Select[Range[2000], SquareFreeQ[#] && And @@ PrimeQ[2# + {-1, 1}] &] (* Amiram Eldar, Dec 19 2019 *)
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PROG
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(Magma) [k:k in [1..2000]|IsSquarefree(k) and IsPrime(2*k-1) and IsPrime(2*k+1)]; // Marius A. Burtea, Dec 19 2019
(PARI) isok(k) = issquarefree(k) && isprime(2*k-1) && isprime(2*k+1); \\ Michel Marcus, Jul 25 2022
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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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