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 A165915 #5 Aug 10 2015 00:26:01 %S A165915 0,1,1,1,1,2,2,1,2,3,3,1,3,4,3,1,4,4,6,2,3,6,5,1,6,8,6,2,7,6,7,2,5,10, %T A165915 7,2,10,11,6,1,10,8,14,4,5,12,11,2,12,13,10,4,15,11,8,1,9,17,17,2,16, %U A165915 16,7,5,11,11,21,6,9,12,15,1,19,23,12,6,13,14,21,3,18,24,24,4,14 %N A165915 a(n) = number of squarefree nonzero quadratic residues of n. %H A165915 C. H. Gribble, <a href="/A165915/b165915.txt">Table of n, a(n) for n=1,...,1000</a>. %Y A165915 Cf. A165913. %K A165915 nonn %O A165915 1,6 %A A165915 _Christopher Hunt Gribble_, Sep 30 2009 %E A165915 a(1) added and definition corrected by _Christopher Hunt Gribble_, Oct 05 2009