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A249305
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Primes p such that 2^p - p^2 is not squarefree.
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0
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OFFSET
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1,1
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COMMENTS
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Sequence is infinite, containing all primes equal to 2, 4, 89, or 115 mod 147. - Charles R Greathouse IV, Oct 28 2014
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LINKS
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Table of n, a(n) for n=1..6.
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FORMULA
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a(n) < (21 + e)n log n for any e > 0 and all large enough n. - Charles R Greathouse IV, Oct 28 2014
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EXAMPLE
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2 is in this sequence because 2 is prime and 2^2 - 2^2 = 0 is not squarefree.
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PROG
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(MAGMA) [n: n in [3..269] | IsPrime(n) and not IsSquarefree(2^n - n^2)];
(PARI) is(n)=isprime(n) && !issquarefree(2^n-n^2) \\ Charles R Greathouse IV, Oct 28 2014
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CROSSREFS
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Cf. A005117, A024012.
Sequence in context: A139881 A161676 A235467 * A023302 A041967 A226768
Adjacent sequences: A249302 A249303 A249304 * A249306 A249307 A249308
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KEYWORD
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nonn,more,changed
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AUTHOR
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Juri-Stepan Gerasimov, Oct 25 2014
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EXTENSIONS
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a(5)-a(6) from Charles R Greathouse IV, Oct 28 2014
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STATUS
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approved
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