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A166381 a(n) = Sum_{j>n} floor(n^2/j).

%I A166381 #14 May 11 2016 00:42:31
%S A166381 0,2,7,17,31,52,76,108,146,191,242,301,364,437,518,605,700,804,914,
%T A166381 1034,1160,1295,1438,1594,1751,1921,2098,2288,2483,2688,2898,3119,
%U A166381 3350,3593,3845,4103,4369,4647,4937,5234,5540,5854,6178,6512,6859
%N A166381 a(n) = Sum_{j>n} floor(n^2/j).
%H A166381 G. C. Greubel, <a href="/A166381/b166381.txt">Table of n, a(n) for n = 1..1000</a>
%F A166381 a(n) = Sum_{i=1..n} floor(n*(n-i)/i). - _Wesley Ivan Hurt_, Jan 30 2016
%p A166381 A166381 := proc(n)
%p A166381     add( floor(n^2/j),j=n+1..n^2) ;
%p A166381 end proc: # _R. J. Mathar_, Jul 21 2015
%t A166381 Table[Sum[Floor[n (n - i)/i], {i, n}], {n, 100}]
%Y A166381 Column sums of A166373.
%K A166381 nonn,easy
%O A166381 1,2
%A A166381 _Christopher Hunt Gribble_, Oct 13 2009