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 A068161 #14 Sep 02 2025 16:26:55
%S A068161 3,33533,3331333,3333133333,333331033333,33333362333333,
%T A068161 333333313333333,333333332933333333,33333333316333333333,
%U A068161 3333333333133333333333,33333333333733333333333
%N A068161 Smallest prime beginning and ending in at least n 3's.
%H A068161 Harvey P. Dale, <a href="/A068161/b068161.txt">Table of n, a(n) for n = 1..100</a>
%e A068161 a(2) = 33533 is a prime that starts with 33 and ends in 33 (two 3's).
%t A068161 Join[{3},Table[With[{c=PadRight[{},n,3]},Module[{k=1},While[!PrimeQ[FromDigits[Join[c,IntegerDigits[k],c]]],k++];FromDigits[Join[c,IntegerDigits[k],c]]]],{n,2,15}]] (* _Harvey P. Dale_, Sep 02 2025 *)
%Y A068161 Cf. A068160.
%K A068161 base,nonn,changed
%O A068161 1,1
%A A068161 _Amarnath Murthy_, Feb 24 2002
%E A068161 Corrected and extended by _Robert Gerbicz_, Sep 06 2002