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 A232657 #24 Aug 12 2015 02:38:20 %S A232657 100,874,1000,1286,3040,3721,3805,3922,4468,6412,7014,7852,8338 %N A232657 Numbers producing at least 4 primes by proper concatenation of decrements. %C A232657 The very simplest example of the type of prime concerned is 43, but 100 (see Example) is the first value to produce 4 primes. 1000 is the first to do so in the fastest way possible. Proper concatenation first excludes 73 from this list, as the stem--initial--value in concatenation is itself excluded from consideration. %C A232657 8338 is the first value to produce 5 primes, with terminal values 8323, 8293, 8079, 7561 and 6519. %e A232657 100 yields four primes in this way: 100 99, 100 99 98 97, 100 99 98 97 96 95 94 93 92 91, and 100 99 98 97...62 61. As the first value to do so properly, a(1)=100. %o A232657 (PARI) is(n)=my(t=Str(n),s=4); while(n--,t=Str(t,n); if(isprime(eval(t)) && s--==0, return(1))); 0 \\ _Charles R Greathouse IV_, Feb 18 2014 %Y A232657 Cf. A152396, A152397, A172257. %K A232657 nonn,base,more %O A232657 1,1 %A A232657 _James G. Merickel_, Nov 27 2013