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 A104491 #4 Mar 30 2012 18:40:27 %S A104491 2,5,13,19,23,37,67,71,83,107,109,113,139,157,173,199,271 %N A104491 Prime numbers n for which the square excess of the n-th prime is prime. %F A104491 n such that A102821(n) is prime. n such that A053186(A000040(n)) is an element of A000040. %e A104491 199 is an element of this sequence because 199 is prime and the 199th prime is 1217 and 1217 - 34^2 = 61 and 61 is prime, while 1217 - 35^2 = -8. %Y A104491 Cf. A000040, A053186, A102821. %K A104491 easy,nonn %O A104491 1,1 %A A104491 _Jonathan Vos Post_, Mar 10 2005