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 A101249 #10 Jan 24 2020 10:55:16
%S A101249 577,5711,5717,5737,5741,5743,5779,5783,57107,57131,57139,57149,57163,
%T A101249 57173,57179,57191,57193,57223,57241,57251,57269,57271,57283,57331,
%U A101249 57347,57349,57367,57373,57383,57389,57397,57457,57467,57487,57503
%N A101249 Primes that are a concatenation of 5, 7 and a prime.
%H A101249 Daniel Starodubtsev, <a href="/A101249/b101249.txt">Table of n, a(n) for n = 1..10000</a>
%H A101249 Peter Alfeld, <a href="http://www.math.utah.edu/~alfeld/math/p10000.html">The 10,000 smallest prime numbers</a>.
%e A101249 5711 is a prime concatenated from the primes 5,7 and 11.
%t A101249 Select[ Table[ FromDigits[ Flatten[ IntegerDigits /@ {5, 7, Prime[n]}]], {n, 100}], PrimeQ[ # ] &] (* _Robert G. Wilson v_, Dec 20 2004 *)
%Y A101249 Cf. A100607, A101218, A101219, A101250, A101251, A101252.
%K A101249 nonn,base,easy
%O A101249 1,1
%A A101249 _Parthasarathy Nambi_, Dec 16 2004
%E A101249 Extended by _Ray Chandler_ and _Robert G. Wilson v_, Dec 22 2004