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A049233
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Primes p such that p + 2 is squarefree.
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6
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3, 5, 11, 13, 17, 19, 29, 31, 37, 41, 53, 59, 67, 71, 83, 89, 101, 103, 107, 109, 113, 127, 131, 137, 139, 149, 157, 163, 179, 181, 191, 193, 197, 199, 211, 227, 229, 233, 239, 251, 257, 263, 269, 271, 281, 283, 293, 307, 311, 317, 337, 347, 353, 379, 383, 389
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OFFSET
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1,1
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COMMENTS
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This sequence is infinite and its relative density in the sequence of primes is equal to 2 * Product_{p prime} (1-1/(p*(p-1))) = 2 * A005596 = 0.747911... (Mirsky, 1949). - Amiram Eldar, Dec 29 2020
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LINKS
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Denis Xavier Charles, Sieve Methods, Master's Thesis, 2000, p. 93.
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MAPLE
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MATHEMATICA
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PROG
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(PARI) isok(p) = isprime(p) && issquarefree(p+2); \\ Michel Marcus, Dec 31 2013
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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