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 A289994 #32 Mar 03 2024 10:16:23 %S A289994 1,2,7,11,19,13,9,21,43,3,31,49,17,37,29,41,27,39,67,33,81,53,51,23, %T A289994 89,91,59,47,73,61,87,99,79,63,117,113,77,127,103,93,111,71,69,101, %U A289994 147,57,97,133,119,121,139,131,107,157,151,123,153,83,143,169,109,137 %N A289994 a(1) = 1, a(2) = 2, a(n) = smallest number not occurring earlier such that the concatenation a(n-2), a(n-1) and a(n) is a prime. %H A289994 Seiichi Manyama, <a href="/A289994/b289994.txt">Table of n, a(n) for n = 1..1000</a> %e A289994 127, 2711, 71119, 111913, ... are primes. %Y A289994 Cf. A075607, A073676, A083754, A110772. %K A289994 nonn,base %O A289994 1,2 %A A289994 _Seiichi Manyama_, Sep 02 2017