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 A262552 #15 Nov 03 2018 13:28:54 %S A262552 11,17,157,3631 %N A262552 Numbers n such that the concatenation of the decimal numbers 1 through n, but omitting 5, is a prime. %C A262552 The corresponding primes are the primes in A262575. %C A262552 The actual values of a(1) to a(4) are also primes, although that is not a necessary condition for a number to belong to this sequence. Not all the terms of A262300 are primes, for example. %C A262552 Probabilistic arguments suggest the sequence is infinite. %C A262552 a(5) > 10000. - _Robert Price_, Nov 03 2018 %e A262552 The first two terms correspond to the primes 123467891011 and 123467891011121314151617. %e A262552 a(3) corresponds to a 362-digit prime, a(4) to a 13416-digit probable prime. These two terms were found by _David Broadhurst_ on Oct 08 2015. %Y A262552 Cf. A262575, A262300, A007908. %K A262552 nonn,base,more %O A262552 1,1 %A A262552 _N. J. A. Sloane_, Oct 09 2015