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Numbers k such that 6k+13 is prime and 12k+13 is also prime.
1

%I #9 Jan 23 2017 18:00:07

%S 0,4,5,8,14,15,19,25,28,30,33,35,44,49,50,54,60,68,70,85,88,93,99,100,

%T 103,120,123,133,140,144,145,149,154,168,170,173,175,179,184,190,198,

%U 215,228,235,245,253,259,264,268,274,275,280,285,288,294

%N Numbers k such that 6k+13 is prime and 12k+13 is also prime.

%H Ivan Neretin, <a href="/A145488/b145488.txt">Table of n, a(n) for n = 1..10000</a>

%F a(n) = (A145474(n)-13)/12.

%p select(k -> isprime(6*k+13) and isprime(12*k+13), [$0..1000]); # _Robert Israel_, Jan 23 2017

%t aa = {}; k = 13; Do[If[PrimeQ[(k + Prime[n])/2], AppendTo[aa, (Prime[n] - k)/12]], {n, 1, 500}]; aa

%Y Cf. A063908-A063913, A092109, A145471-A145490.

%K nonn

%O 1,2

%A _Artur Jasinski_, Oct 11 2008

%E Definition corrected by _Ivan Neretin_, Jan 23 2017