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 A224223 #15 Dec 12 2015 12:32:09 %S A224223 2,3,5,13,19,31,41,449,127,197,103,139,149,1879,277,173,83,5119,389, %T A224223 1777,223,659,1277,839,313,937,1091,367,1201,5527,773,4993,1151,7561, %U A224223 2843,4507,677,4799,977,5107,4493,15679,7253,26029,3011,1039,5309,3527 %N A224223 a(0)=2; for n>0, a(n) = smallest prime not occurring earlier in the sequence such that a(n-1)+a(n) is a multiple of n^2. If no such prime exists, the sequence terminates. %C A224223 Is this sequence infinite and, if so, is it a permutation of the primes? The answers are probably Yes and No (7 has not appeared after 10000 terms). Compare A134204. %H A224223 N. J. A. Sloane, <a href="/A224223/b224223.txt">Table of n, a(n) for n = 0..9999</a> %Y A224223 Cf. A134204, A224221, A224222, A224229. %K A224223 nonn,look %O A224223 0,1 %A A224223 _Daniel Drucker_ and _N. J. A. Sloane_, Apr 05 2013