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 A032726 #11 Jul 28 2021 04:25:56
%S A032726 0,3,4,7,9,10,12,22,24,25,27,28,31,39,40,42,43,45,48,49,54,55,57,60,
%T A032726 61,66,69,70,75,78,87,88,94,97,99,105,106,111,114,115,123,127,129,132,
%U A032726 136,139,148,151,154,157,168,169,171,177,178,183,190,193,195,196,204
%N A032726 Numbers k such that k prefixed by '1' and followed by '9' is a prime.
%t A032726 Select[Range[0,200],PrimeQ@FromDigits[Join[{1},IntegerDigits@#,{9}]]&] (* _Giorgos Kalogeropoulos_, Jul 28 2021 *)
%K A032726 nonn,base
%O A032726 1,2
%A A032726 _Patrick De Geest_, May 15 1998