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 A156707 #7 Nov 24 2019 23:47:37
%S A156707 -1,1,-1,0,-1,1,0,1,-1,0,-1,0,0,1,-1,0,0,1,0,1,-1,0,-1,0,0,1,0,0,-1,1,
%T A156707 0,0,-1,0,-1,1,0,0,-1,0,-1,0,0,1,0,0,0,1,0,1,-1,0,-1,1,0,1,0,0,0,0,0,
%U A156707 0,-1,0,-1,0,0,1,-1,0,0,0,0,1,-1,0,0,1,0,0,-1,0,-1,0,0,1,0,0,-1,1,0,0,0,0,-1
%N A156707 For all numbers k(n) congruent to +1 or -1 (mod 4) starting with k(n) = {3,5,7,9,11,...}, a(k(n)) is the congruence (mod 4) if k(n) is prime and 0 if k(n) is composite.
%C A156707 Expression for k(n): k(n) = 4*ceiling(n/2) + (-1)^n, so the parity of n gives us the congruence (mod 4) of k(n). - _Daniel Forgues_, Mar 01 2009
%H A156707 Daniel Forgues, <a href="/A156707/b156707.txt">Table of n, a(n) for n = 1..49999</a>
%Y A156707 The absolute values of this sequence give A101264 (for n > 0.) The partial sums of this sequence give A156749. - _Daniel Forgues_, Mar 01 2009
%K A156707 sign
%O A156707 1,1
%A A156707 _Daniel Forgues_, Feb 13 2009, Feb 14 2009