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 A131261 #13 Sep 16 2015 12:58:52
%S A131261 3,5,7,11,13,17,19,23,41,31,29,37,47,83,43,107,53,151,101,89,71,97,79,
%T A131261 59,61,139,173,313,163,127,113,73,311,283,193,157,131,239,103,443,197,
%U A131261 541,257,431,229,401,887,241,191,397,353,463,109,421,227,433,631,167
%N A131261 a(0)=3; for n>0, a(n) = smallest odd prime not occurring earlier in the sequence such that a(n-1)+a(n) is a multiple of n.
%C A131261 Is this sequence infinite and, if so, is it a permutation of the odd primes?
%C A131261 An analog of A134204, but using only the odd primes.
%H A131261 Olivier Gérard, <a href="/A131261/b131261.txt">Table of n, a(n) for n = 0..1000</a>
%t A131261 a = {3}; For[n = 1, n < 60, n++, i = 2; While[Length[Intersection[{Prime[i]}, a]] == 1 || Not[Mod[a[[ -1 ]] + Prime[i], n] == 0], i++ ]; AppendTo[a, Prime[i]]]; a (* _Stefan Steinerberger_, Oct 30 2007 *)
%Y A131261 Cf. A134204.
%K A131261 nonn
%O A131261 0,1
%A A131261 _David Applegate_, Oct 26 2007