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A191626 Integers n such that both 6n and 36n fall between pairs of twin primes, that is, 6n-1, 6n+1, 36n-1, and 36n+1 are prime. 4

%I #26 Nov 21 2013 12:50:18

%S 2,3,5,12,23,32,45,52,58,72,107,137,138,175,182,270,278,287,325,562,

%T 577,578,597,703,747,753,872,980,1022,1160,1325,1372,1438,1477,1540,

%U 1892,1950,2007,2018,2313,2335,2387,2597,2608,2705,2742,2782,3008

%N Integers n such that both 6n and 36n fall between pairs of twin primes, that is, 6n-1, 6n+1, 36n-1, and 36n+1 are prime.

%C Infinite under Dickson's conjecture. [_Charles R Greathouse IV_, Jul 24 2011]

%H Andrea Raffetti, <a href="/A191626/b191626.txt">Table of n, a(n) for n = 1..999</a>

%e 5 is in the list because 5*6=30, 5*36=180 and both fall between a pair of twin primes (29,31 and 179,181).

%t Select[Range[3100],And@@PrimeQ[{6#+1,6#-1,36#+1,36#-1}]&] (* _Harvey P. Dale_, Jul 27 2011 *)

%Y Subsequence of A002822.

%Y Cf. A014574.

%K nonn

%O 1,1

%A _Andrea Raffetti_, Jul 11 2011

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Last modified March 28 14:38 EDT 2024. Contains 371254 sequences. (Running on oeis4.)