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Number of pairs {i,j}, i>1, j>1, such that ij < n^2.
3

%I #7 Nov 21 2013 12:46:35

%S 0,3,9,20,33,54,77,108,142,186,228,285,342,409,481,563,644,742,837,

%T 946,1060,1184,1308,1449,1592,1744,1903,2076,2240,2432,2618,2818,3028,

%U 3246,3461,3702,3940,4192,4444,4719,4980,5274,5559

%N Number of pairs {i,j}, i>1, j>1, such that ij < n^2.

%H Harvey P. Dale, <a href="/A037048/b037048.txt">Table of n, a(n) for n = 2..1000</a>

%F Sum(floor((n^2-1)/i)+1-i, i=2..n)

%e f(3)=3 because the only pairs of 2 numbers > 1 that are < 9 are (2,2) (2,3) (2,4).

%t Table[Sum[Floor[(n^2-1)/i]+1-i,{i,2,n}],{n,2,45}] (* _Harvey P. Dale_, Oct 10 2011 *)

%Y Cf. A034806, A037092.

%K nonn

%O 2,2

%A Joe K. Crump (joecr(AT)carolina.rr.com)