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 A125744 Primes p such that (3^p + 3^((p + 1)/2) + 1)/7 is prime. 2
 11, 37, 47, 97, 167, 877, 2027, 2293, 3011, 6803, 8423, 50221, 152809, 505823 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS PrimePi[ a(n) ] = {5, 12, 15, 25, 39, 151, 307, 341, ...}. LINKS Table of n, a(n) for n=1..14. Henri & Renaud Lifchitz, PRP Records. MATHEMATICA Do[p=Prime[n]; f=(3^p+3^((p+1)/2)+1)/7; If[PrimeQ[f], Print[{n, p}]], {n, 1, 341}] CROSSREFS Cf. A125743 = 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: A233403 A054293 A072859 * A116057 A099227 A122728 Adjacent sequences: A125741 A125742 A125743 * A125745 A125746 A125747 KEYWORD hard,more,nonn AUTHOR Alexander Adamchuk, Dec 04 2006 EXTENSIONS a(9)-a(12) from Lelio R Paula (lelio(AT)sknet.com.br), May 09 2008 a(13)-a(14) from Serge Batalov, Mar 07 2014 STATUS approved

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Last modified June 4 12:12 EDT 2023. Contains 363128 sequences. (Running on oeis4.)