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 A331003 #7 Jan 06 2020 09:15:14 %S A331003 0,1,1,-1,-1,2,2,-2,-2,2,2,-2,-2,3,3,-3,-3,2,2,-4,-4,3,3,-3,-3,4,4,-3, %T A331003 -3,4,4,-4,-4,4,4,-5,-5,3,3,-5,-5,5,5,-6,-6,3,3,-6,-6,4,4,-5,-5,5,5, %U A331003 -6,-6,6,6,-7,-7,3,3,-7,-7,5,5,-6,-6,5,5,-6,-6,5,5 %N A331003 a(n) is the imaginary part of f(n) (as defined in A330779). %H A331003 Rémy Sigrist, <a href="/A331003/b331003.txt">Table of n, a(n) for n = 0..10000</a> %H A331003 Rémy Sigrist, <a href="/A331003/a331003.gp.txt">PARI program for A331003</a> %F A331003 a(2*k+2) = a(2*k+1) for any k >= 0. %F A331003 a(2*k+1) = a(2*k) + A330779(2*k+1) * (-1)^k for any k >= 0. %o A331003 (PARI) See Links section. %Y A331003 Cf. A330779. %K A331003 sign %O A331003 0,6 %A A331003 _Rémy Sigrist_, Jan 05 2020