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%I #13 Sep 06 2017 11:30:16
%S 7,11,17,19,23,29,31,41,47,53,59,67,71,83,89,101,107,113,127,131,137,
%T 139,149,167,179,181,191,197,199,211,227,233,239,251,257,263,269,281,
%U 293,307,311,317,347
%N Chen primes p such that there are Chen primes p > q > r in arithmetic progression.
%C Green & Tao prove that this sequence is infinite.
%H Charles R Greathouse IV, <a href="/A269256/b269256.txt">Table of n, a(n) for n = 1..10000</a>
%H Ben Green and Terence Tao, <a href="http://jtnb.cedram.org/item?id=JTNB_2006__18_1_147_0">Restriction theory of the Selberg sieve, with applications</a>, Journal de théorie des nombres de Bordeaux 18:1 (2006), pp. 147-182.
%e 19 is in the sequence since 3 < 11 < 19, 19 - 11 = 11 - 3, all three are prime, and 3+2, 11+2, and 19+2 are each either prime or semiprime.
%o (PARI) issemi(n)=bigomega(n)==2
%o ischen(n)=isprime(n) && (isprime(n+2) || issemi(n+2))
%o is(n)=if(!ischen(n), return(0)); forprime(p=2,n-4, if((p+n)%4==2 && ischen(p) && ischen((p+n)/2), return(1))); 0
%Y Subsequence of A109611. This is the Chen prime analog of A216495.
%Y Cf. A291525.
%K nonn
%O 1,1
%A _Charles R Greathouse IV_, Jul 12 2016
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