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 A093011 #15 Sep 08 2022 08:45:13
%S A093011 3,13,113,11113,111111113,11111111113,111111111111111111111113,
%T A093011 111111111111111111111111111111111111111111111111111111111111111111111111111111111113
%N A093011 Primes of the form 10*R_k + 3, where R_k is the repunit (A002275) of length k.
%C A093011 Primes of the form 2 + (10^k - 1)/9, k > 0. - _Vincenzo Librandi_, Dec 13 2011
%H A093011 Vincenzo Librandi, <a href="/A093011/b093011.txt">Table of n, a(n) for n = 1..9</a>
%H A093011 Makoto Kamada, <a href="https://stdkmd.net/nrr/1/11113.htm#prime">Prime numbers of the form 11...113</a>.
%H A093011 <a href="/index/Pri#Pri_rep">Index entries for primes involving repunits</a>
%t A093011 Select[Table[(((10^n-1)/ 9)+2),{n,1,900}],PrimeQ] (* _Vincenzo Librandi_, Dec 13 2011 *)
%o A093011 (Magma) [a: n in [1..100] | IsPrime(a) where a is ((10^n-1) div 9)+2 ]; // _Vincenzo Librandi_, Dec 13 2011
%Y A093011 Cf. A056654 (corresponding k).
%K A093011 nonn
%O A093011 1,1
%A A093011 _Rick L. Shepherd_, Mar 14 2004