%I
%S 2,5,11,13,16,28,29,30,35,36,42,44,50,51,55,57,73,86,104,121,125,128,
%T 135,140,147,148,157,158,160,161,165,168,179,193,204,205,209,223,244,
%U 247,249,251,255,264,271,273,277,281,282,290,302,304,310,312,313,316
%N Numbers k such that 210*k + 1 are twin primes.
%H Amiram Eldar, <a href="/A075749/b075749.txt">Table of n, a(n) for n = 1..10000</a>
%e k = 2 is a term since 210*2  1 = 419 and 210*2 + 1 = 421 are twin primes.
%t Select[Range[6! ],PrimeQ[210*#1]&&PrimeQ[210*#+1]&] (* _Vladimir Joseph Stephan Orlovsky_, Apr 08 2010 *)
%o (PARI) isok(n) = isprime(210*n+1) && isprime(210*n1); \\ _Michel Marcus_, Jan 14 2015
%o (MAGMA) [k:k in [1..320] IsPrime(210*k1) and IsPrime(210*k+1)]; // _Marius A. Burtea_, Jan 01 2020
%Y Cf. A002822 (with 6*k + 1), A176114 (with 30*k + 1).
%K easy,nonn
%O 1,1
%A _Zak Seidov_, Oct 08 2002
