This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A139690 #19 Apr 19 2025 14:39:06
%S A139690 4,5,7,9,13,15,19,21,25,31,33,39,43,49,55,61,69,73,85,91,103,109,111,
%T A139690 115,129,133,139,141,151,159,169,181,183,193,199,201,213,229,235,241,
%U A139690 253,259,265,271,283,295,309,313,319,339,349,355,361,381,391,403,411
%N A139690 a(n) = A109611(n) + 2.
%H A139690 Reinhard Zumkeller, <a href="/A139690/b139690.txt">Table of n, a(n) for n = 1..1000</a>
%H A139690 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/ChenPrime.html">Chen Prime</a>
%F A139690 A010051(a(n)) = A139689(n); A064911(a(n)) = 1 - A139689(n);
%F A139690 A001222(a(n)) = 2 - A139689(n).
%t A139690 Cases[Import["https://oeis.org/A109611/b109611.txt", "Table"], {_, _}][[All, 2]] + 2 (* _Robert Price_, Apr 19 2025 *)
%o A139690 (PARI) list(lim)=my(v=List(),t); forprime(p=2,lim\2, forprime(q=2,min(p,lim\p), if(isprime(t=p*q-2), listput(v,t+2)))); t=2; forprime(p=3,lim, if(p-t==2, listput(v,p)); t=p); Set(v) \\ _Charles R Greathouse IV_, Jan 19 2017
%Y A139690 Intersection of A052147 and A037143; A006512 is a subsequence.
%Y A139690 Cf. A109611.
%K A139690 nonn
%O A139690 1,1
%A A139690 _Reinhard Zumkeller_, Apr 29 2008