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 A104718 #3 Mar 30 2012 18:40:27 %S A104718 311,513,1119,2331,2937,5361,5967,7179,8997,101109,131139,149157, %T A104718 173181,191199,233241,263271,269277,359367,389397,401409,431439, %U A104718 449457,479487,491499,563571,569577,593601,599607,653661,683691,701709,719727,743751 %N A104718 Concatenations of pairs of primes that differ by 8. %C A104718 There are no primes in this sequence after a(1) = 311, as all values thereafter are divisible by 3. Semiprimes in this sequence include: a(3) = 1119 = 3 * 373 a(6) = 5361 = 3 * 1787, a(8) = 7179 = 3 * 2393, a(9) = 8997 = 3 * 2999, a(10) = 101109 = 3 * 33703, a(13) = 173181 = 3 * 57727, a(15) = 233241 = 3 * 77747, a(17) = 269277 = 3 * 89759, a(21) = 431439 = 3 * 143813, a(26) = 569577 = 3 * 189859, a(35) = 821829 = 3 * 273943. %F A104718 a(n) = A023202(n) concatenated with A023202(n)+8. %Y A104718 Cf. A000040, A001358, A023202, A103195, A103206, A104719. %K A104718 base,easy,nonn %O A104718 1,1 %A A104718 _Jonathan Vos Post_, Mar 20 2005