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 A034849 #15 Aug 01 2017 02:52:04
%S A034849 7,11,17,19,23,29,31,41,43,47,53,59,67,71,79,83,89,97,101,103,107,109,
%T A034849 113,127,131,137,139,149,151,163,167,173,179,181,191,197,199,211,223,
%U A034849 227,229,233,239,241,251,257,263,269,271,281,283,293,307,311,317,331
%N A034849 a(n) = 1 + 2*A034784(n).
%C A034849 The terms are odd prime numbers.
%H A034849 Michael De Vlieger, <a href="/A034849/b034849.txt">Table of n, a(n) for n = 1..10000</a>
%t A034849 1 + 2 Position[#, 2] &@ Table[k = 1; While[! PrimeQ[k n + 1], k++]; k, {n, 165}] // Flatten (* _Michael De Vlieger_, Jul 31 2017 *)
%o A034849 (PARI) lista(nn) = for (n=1, nn, if (isprime(p=2*n+1) && !isprime(n+1), print1(p, ", "));); \\ _Michel Marcus_, Aug 01 2017
%Y A034849 Cf. A034693, A034694, A034784.
%K A034849 nonn
%O A034849 1,1
%A A034849 _Labos Elemer_
%E A034849 Edited by _N. J. A. Sloane_, Oct 27 2012