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 A163897 #15 Aug 29 2020 07:14:03 %S A163897 0,0,2,4,-2,-8,-6,0,0,0,2,16,16,12,6,0,0,8,10,24,28,16,0,0,0,0,10,28, %T A163897 24,16,32,40,48,48,24,20,-2,-24,-40,-36,-40,-44,-64,-60,-56,-48,-42, %U A163897 -56,-42,-36,-20,-16,-8,0,16,8,14,36,34,24,28,28,18,24,16,8,-8,0,-10 %N A163897 a(n) = A163531(n)-A163547(n). %C A163897 This sequence gives the difference of squares of distance from the origin to the n-th term, in the Peano curve (A163334) and the Hilbert curve (A163357) on an N x N grid. Because the Hilbert curve is based on powers of 4 and the Peano curve on powers of 9, the graph of this sequence contains dramatic swings. [Edited to Peano vs Hilbert by _Kevin Ryde_, Aug 28 2020] %H A163897 Antti Karttunen, <a href="/A163897/b163897.txt">Table of n, a(n) for n = 0..65535</a> %Y A163897 Cf. A165480 (positions of 0's). %K A163897 sign %O A163897 0,3 %A A163897 _Antti Karttunen_, Sep 19 2009