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 A135993 #19 May 14 2020 22:49:29 %S A135993 0,1,0,1,0,0,1,0,0,0,1,1,0,0,0,1,0,0,1,0,0,1,1,1,0,0,0,0,1,1,1,0,0,0, %T A135993 1,1,0,0,0,1,0,1,0,0,0,1,1,1,0,0,0,0,1,1,1,1,0,0,0,1,1,0,0,0,0,0,1,0, %U A135993 0,1,1 %N A135993 a(0) = 0; a(n) = (floor(n/S2(n))) mod 2 for n >= 1, where S2(n) is the binary weight of n. %H A135993 J.-P. Allouche, J. Shallit and J. Sondow, <a href="http://arxiv.org/abs/math/0512399">Summation of Series Defined by Counting Blocks of Digits</a>, arXiv:math/0512399 [math.NT], 2005-2006. %H A135993 J.-P. Allouche, J. Shallit and J. Sondow, <a href="http://dx.doi.org/10.1016/j.jnt.2006.06.001">Summation of series defined by counting blocks of digits</a>, J. Number Theory 123 (2007), 133-143. %H A135993 Jonathan Sondow and Petros Hadjicostas, <a href="http://arxiv.org/abs/math/0610499">The Generalized-Euler-Constant Function (z) and a Generalization of Somos's Quadratic Recurrence Constant</a>, arXiv:math/0610499 [math.CA], 2006. %H A135993 Jonathan Sondow and Petros Hadjicostas, <a href="http://dx.doi.org/10.1016/j.jmaa.2006.09.081">The generalized-Euler-constant function gamma(z) and a generalization of Somos's quadratic recurrence constant</a>, J. Math. Anal. Appl. 332 (2007), 292-314. %F A135993 a(n) = A135941(n) mod 2 for n > 0. - _Michel Marcus_, Feb 04 2016 %e A135993 a(17) = floor(17/2) mod 2 = 0. %e A135993 a(18) = floor(18/2) mod 2 = 1. %o A135993 (PARI) a(n) = if (n==0, 0, n\hammingweight(n) % 2); \\ _Michel Marcus_, Feb 04 2016 %Y A135993 Cf. A007953, A010060, A135941. %K A135993 easy,nonn %O A135993 0,1 %A A135993 _Ctibor O. Zizka_, Mar 03 2008 %E A135993 Converted references into links - _R. J. Mathar_, Oct 30 2009