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 A123738 #11 Sep 08 2022 08:45:28 %S A123738 -1,0,-1,0,-1,0,-1,-2,-1,-2,-1,-2,-1,-2,-3,-2,-3,-2,-3,-2,-3,-4,-3,-4, %T A123738 -3,-4,-3,-4,-5,-4,-5,-4,-5,-4,-5,-6,-5,-6,-5,-6,-5,-6,-7,-6,-7,-6,-7, %U A123738 -6,-7,-8,-7,-8,-7,-8,-7,-8,-9,-8,-9,-8,-9,-8,-9,-10,-9,-10,-9,-10,-9,-10,-11,-10,-11,-10,-11,-10,-11,-12,-11,-12 %N A123738 Partial sums of (-1)^floor(n*Pi). %H A123738 T. D. Noe, <a href="/A123738/b123738.txt">Table of n, a(n) for n=1..10000</a> %H A123738 Kevin O'Bryant, Bruce Reznick and Monika Serbinowska, <a href="https://arxiv.org/abs/math/0308087">Almost alternating sums</a>, arXiv:math/0308087 [math.NT], 2003-2005. %H A123738 Kevin O'Bryant, Bruce Reznick and Monika Serbinowska, <a href="http://www.jstor.org/stable/27642030">Almost alternating sums</a>, Amer. Math. Monthly, Vol. 113 (October 2006), 673-688. %t A123738 Rest[FoldList[Plus,0,(-1)^Floor[Pi*Range[120]]]] %o A123738 (PARI) vector(130, n, sum(j=1,n, (-1)^(j\(1/Pi))) ) \\ _G. C. Greubel_, Sep 05 2019 %o A123738 (Magma) R:= RealField(20); [&+[(-1)^Floor(j*Pi(R)): j in [1..n]]: n in [1..130]]; // _G. C. Greubel_, Sep 05 2019 %o A123738 (Sage) [sum((-1)^floor(j*pi) for j in (1..n)) for n in (1..130)] # _G. C. Greubel_, Sep 05 2019 %Y A123738 Cf. A123724 (sum for 2^(1/3)), A123737 (sum for sqrt(2)), A123739 (sum for e). %K A123738 easy,sign %O A123738 1,8 %A A123738 _T. D. Noe_, Oct 11 2006