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