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A125743
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Primes p such that (3^p - 3^((p + 1)/2) + 1)/7 is prime.
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2
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5, 31, 53, 163, 509, 1061, 13627, 20047, 28411, 50993, 71453, 272141, 1353449
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OFFSET
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1,1
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COMMENTS
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PrimePi[ a(n) ] = {3, 11, 16, 38, 97, 178,...}.
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LINKS
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Table of n, a(n) for n=1..13.
Henri & Renaud Lifchitz, PRP Records.
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MATHEMATICA
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Do[p=Prime[n]; f=(3^p-3^((p+1)/2)+1)/7; If[PrimeQ[f], Print[{n, p}]], {n, 1, 178}]
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CROSSREFS
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Cf. A125744 = Primes p such that (3^p + 3^((p + 1)/2) + 1)/7 is prime. Cf. A125738 = Primes p such that 3^p - 3^((p + 1)/2) + 1 is prime. Cf. A125739 = Primes p such that 3^p + 3^((p + 1)/2) + 1 is prime. Cf. A007670, A007671, A124165, A125742.
Sequence in context: A238674 A245523 A147033 * A332788 A333243 A078686
Adjacent sequences: A125740 A125741 A125742 * A125744 A125745 A125746
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KEYWORD
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hard,more,nonn
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AUTHOR
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Alexander Adamchuk, Dec 04 2006
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EXTENSIONS
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a(6)-a(11) from Lelio R Paula (lelio(AT)sknet.com.br), May 08 2008
a(12) from Serge Batalov, Mar 07 2014
a(13) from Serge Batalov, Mar 25 2014
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STATUS
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approved
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