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 A087733 #25 Jun 04 2025 11:07:36
%S A087733 0,1,1,2,4,7,9,12,14,17,19,22,26,31,35,40,46,53,59,66,74,83,91,100,
%T A087733 108,117,125,134,144,155,165,176,186,197,207,218,230,243,255,268,280,
%U A087733 293,305,318,332,347,361,376,392,409,425,442,460,479,497,516,534,553,571
%N A087733 Partial sums of A068639.
%H A087733 Paolo Xausa, <a href="/A087733/b087733.txt">Table of n, a(n) for n = 0..10000</a>
%H A087733 J.-P. Allouche and Jeffrey Shallit, <a href="http://www.math.jussieu.fr/~allouche/kreg2.ps">The Ring of k-regular Sequences, II</a>
%H A087733 J.-P. Allouche and Jeffrey Shallit, <a href="https://doi.org/10.1016/S0304-3975(03)00090-2">The ring of k-regular sequences, II</a>, Theoret. Computer Sci., 307 (2003), 3-29.
%H A087733 Hsien-Kuei Hwang, S. Janson, and T.-H. Tsai, <a href="http://140.109.74.92/hk/wp-content/files/2016/12/aat-hhrr-1.pdf">Exact and asymptotic solutions of the recurrence f(n) = f(floor(n/2)) + f(ceiling(n/2)) + g(n): theory and applications</a>, Preprint, 2016.
%H A087733 Hsien-Kuei Hwang, S. Janson, and T.-H. Tsai, <a href="https://doi.org/10.1145/3127585">Exact and Asymptotic Solutions of a Divide-and-Conquer Recurrence Dividing at Half: Theory and Applications</a>, ACM Transactions on Algorithms, 13:4 (2017), #47.
%F A087733 a(0)=0, a(2n+1) = -a(n)-a(n+1)+n^2+n, a(2n+1) = -2a(n)+n^2+2n+1. - _Ralf Stephan_, Oct 16 2003
%t A087733 Join[{0}, Nest[Accumulate, (-1)^IntegerExponent[Range[100], 2], 2]] (* _Paolo Xausa_, Jun 04 2025 *)
%K A087733 nonn,easy
%O A087733 0,4
%A A087733 _N. J. A. Sloane_, Oct 01 2003
%E A087733 More terms from _Benoit Cloitre_, Oct 04 2003