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 A101218 #11 Jul 01 2025 16:02:57 %S A101218 233,2311,2341,2347,2371,2383,2389,23131,23167,23173,23197,23227, %T A101218 23251,23269,23293,23311,23431,23509,23557,23563,23593,23599,23677, %U A101218 23719,23743,23761,23773,23827,23857,23887,23911,23929,23971,23977,231019 %N A101218 Primes that are a concatenation of 2, 3 and a prime. %H A101218 Harvey P. Dale, <a href="/A101218/b101218.txt">Table of n, a(n) for n = 1..1000</a> %H A101218 Peter Alfeld <a href="http://www.math.utah.edu/~alfeld/math/p10000.html">The 10,000 smallest prime numbers</a>. %e A101218 233 is a prime concatenated from the primes 2,3 and 3 %e A101218 2311 is a prime concatenated from the primes 2,3 and 11 %t A101218 Select[23*10^IntegerLength[#]+#&/@Prime[Range[200]],PrimeQ] (* _Harvey P. Dale_, Jun 09 2013 *) %Y A101218 Cf. A100607, A101219, A101249, A101250, A101251, A101252. %K A101218 nonn,base,easy %O A101218 1,1 %A A101218 _Parthasarathy Nambi_, Dec 14 2004 %E A101218 Extended by _Ray Chandler_, Dec 22 2004