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 A103888 #14 Jan 18 2024 04:28:46
%S A103888 3,8,12,21,23,38,42,45,48,51,54,56,59,69,72,83,86,92,93,105,111,113,
%T A103888 131,135,137,159,161,162,174,176,183,203,207,209,210,228,230,237,245,
%U A103888 246,249,260,264,267,273,287,300,324,327,330,336,341,345,362,386,390,396
%N A103888 Numbers k such that the string 100k001 is prime.
%e A103888 93 is a term, as 10093001 is prime.
%t A103888 Select[Range[400],PrimeQ[FromDigits[Flatten[Prepend[IntegerDigits[1000#+1],{1,0,0}]]]]&] (* _James C. McMahon_, Jan 17 2024 *)
%Y A103888 Cf. A099678.
%K A103888 base,nonn,less
%O A103888 1,1
%A A103888 _Parthasarathy Nambi_, Mar 30 2005
%E A103888 More terms from _David Wasserman_, Apr 24 2008