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A124518 Numbers k such that 10k-1 and 10k+1 are twin primes. 10

%I #17 Oct 31 2019 12:02:54

%S 3,6,15,18,24,27,42,57,60,66,81,102,105,123,129,132,162,195,213,231,

%T 234,255,273,279,297,300,312,330,333,336,339,354,393,402,405,423,426,

%U 465,480,501,510,528,552,564,585,588,609,627,630,636,645,657,666,669,678

%N Numbers k such that 10k-1 and 10k+1 are twin primes.

%C All terms are divisible by 3. - _Robert Israel_, Apr 07 2019

%H Robert Israel, <a href="/A124518/b124518.txt">Table of n, a(n) for n = 1..10000</a>

%p select(t -> isprime(10*t+1) and isprime(10*t-1), [seq(i,i=3..1000,3)]); # _Robert Israel_, Apr 07 2019

%t Select[Range[678], And @@ PrimeQ[{-1, 1} + 10# ] &] (* _Ray Chandler_, Nov 16 2006 *)

%Y Cf. A040040, A045753, A002822, A124065, A124519-A124522, A063983.

%K nonn

%O 1,1

%A _Artur Jasinski_, Nov 04 2006

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Last modified April 19 03:46 EDT 2024. Contains 371782 sequences. (Running on oeis4.)