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 A165580 #2 Mar 31 2012 13:21:19
%S A165580 3,7,23,31,47,71,79,151,167,191,199,239,263,271,311,359,383,431,439,
%T A165580 479,503,599,647,719,743,751,839,863,887,911,919,983,991,1031,1039,
%U A165580 1151,1223,1231,1279,1319,1399,1439,1471,1487,1511,1559,1583,1759
%N A165580 Primes of the form 4n+3 for which Sum_{i=1..u} J(i,4n+3) is never zero for any u in range [1,(2n+1)], where J(i,m) is the Jacobi symbol.
%Y A165580 Setwise difference of A095102 and A165977. Also subset of A165469.
%K A165580 nonn
%O A165580 1,1
%A A165580 _Antti Karttunen_, Oct 06 2009