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 A116589 #12 Sep 27 2017 17:58:21
%S A116589 0,1,4,6,9,15,22,30,36,43,54,66,79,93,108,120,133,151,170,190,211,233,
%T A116589 256,280,300,321,348,376,405,435,466,498,531,565,600,630,661,699,738,
%U A116589 778,819,861,904,948,993,1039,1086,1134,1176,1219,1270,1322,1375,1429,1484,1540
%N A116589 a(n) = Sum{sqrt(n) < i <= n} i - Sum{1 <= i < sqrt(n)} i.
%C A116589 Lim_{n->oo} a(n)/n^2 = 1/2. - _Stefan Steinerberger_, Apr 16 2006
%H A116589 G. C. Greubel, <a href="/A116589/b116589.txt">Table of n, a(n) for n = 1..1000</a>
%t A116589 Table[Sum[i, {i, Ceiling[Sqrt[n]], n}]-Sum[i,{i,1,Floor[Sqrt[n]]}], {n, 1, 10}] (* _Stefan Steinerberger_, Apr 16 2006 *)
%Y A116589 Cf. A079667.
%K A116589 nonn
%O A116589 1,3
%A A116589 _N. J. A. Sloane_, Apr 15 2006