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 A271956 Numbers n such that 2*n*3^n - 1 is prime. 1
 1, 4, 6, 10, 35, 112, 149, 390, 424, 566, 660, 664, 850, 1414, 1436, 1497, 1524, 1904, 5116, 6625, 10944, 12637, 35691, 92304 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS No further terms < 10^5. LINKS Table of n, a(n) for n=1..24. EXAMPLE 1 is in this sequence because 2*1*3^1 - 1 = 5 is prime. MAPLE A271956:=n->`if`(isprime(2*n*3^n-1), n, NULL): seq(A271956(n), n=1..2*10^3); # Wesley Ivan Hurt, Apr 17 2016 MATHEMATICA Select[Range[10000], PrimeQ[2 # 3^# - 1] &] PROG (PARI) is(n)=ispseudoprime(2*n*3^n-1) \\ Charles R Greathouse IV, Jun 13 2017 CROSSREFS Cf. A006553, A266694. Sequence in context: A242565 A032392 A253048 * A242502 A136838 A234276 Adjacent sequences: A271953 A271954 A271955 * A271957 A271958 A271959 KEYWORD nonn,more AUTHOR Ray Chandler, Apr 17 2016 STATUS approved

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Last modified August 8 09:31 EDT 2024. Contains 375018 sequences. (Running on oeis4.)