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 A033920 #7 Oct 06 2019 18:33:21 %S A033920 0,0,0,0,0,3,7,0,3,2,3,7,0,3,7,5,5,0,7,7,7,7,3,0,7,0,3,7,0,13,7,31,37, %T A033920 13,0,5,7,3,67,73,79,0,19,19,97,19,11,23,7,29,23,23,41,5,7,3,2,71,7,2, %U A033920 83,29,7,31,31,31,31,37,47,3,53,59,67,73,79,83,89,97,0,0,41,2,43,43,43 %N A033920 Largest proper substring of n-th prime that is prime (0 if none). %e A033920 p(16)=53, largest prime substring is 5, so a(16)=5. %Y A033920 See A033274 for the 'no prime substring' sequence. %K A033920 nonn,base %O A033920 1,6 %A A033920 _N. J. A. Sloane_ %E A033920 More terms from _Patrick De Geest_, Jun 15 1998