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 A034814 #9 Aug 13 2024 22:53:48 %S A034814 9,51,63,87,111,123,153,177,207,211,239,263,273,289,327,333,343,359, %T A034814 407,471,489,497,513,541,597,621,651,659,663,681,687,693,697,747,753, %U A034814 793,819,831,869,909,977,987,1027,1041,1089,1131,1143,1239,1491,1611 %N A034814 Concatenations C1 and C2 are both prime (see the comment lines). %C A034814 C1 = 'prevprime(k) followed by k'. %C A034814 C2 = 'k followed by prevprime(k)'. %H A034814 Andrew Howroyd, <a href="/A034814/b034814.txt">Table of n, a(n) for n = 1..1000</a> %e A034814 n=747 -> previous prime is 743, thus '743747' and '747743' are both primes. %Y A034814 Intersection of A034808 and A034809. %Y A034814 Cf. A034810-A034821. %K A034814 nonn,base %O A034814 1,1 %A A034814 _Patrick De Geest_, Oct 15 1998 %E A034814 Offset changed by _Andrew Howroyd_, Aug 13 2024