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Numbers k such that 18*k - 1 and 18*k + 1 are twin primes.
5

%I #13 Dec 17 2019 07:37:43

%S 1,4,6,10,11,15,24,29,45,46,49,59,64,71,90,104,111,116,119,126,130,

%T 144,155,165,176,181,185,196,199,204,214,225,231,235,241,249,251,266,

%U 274,276,279,301,314,319,325,326,350,364,365,370,386,396,406,416,420,431

%N Numbers k such that 18*k - 1 and 18*k + 1 are twin primes.

%H Amiram Eldar, <a href="/A137877/b137877.txt">Table of n, a(n) for n = 1..10000</a>

%e 1 is in the sequence since 18*1 - 1 = 17 and 18*1 + 1 = 19 are twin primes.

%t q=18; lst={}; Do[r=n*q; If[PrimeQ[r-1]&&PrimeQ[r+1], AppendTo[lst, n]], {n, 1, 10^3}]; lst (* _Vladimir Joseph Stephan Orlovsky_, Aug 07 2008 *)

%Y Cf. A124519, A135023, A135368, A137876.

%K nonn

%O 1,2

%A _Zak Seidov_, Feb 19 2008