cp's OEIS Frontend

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.

A037048 Number of pairs {i,j}, i>1, j>1, such that ij < n^2.

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%I A037048 #7 Nov 21 2013 12:46:35
%S A037048 0,3,9,20,33,54,77,108,142,186,228,285,342,409,481,563,644,742,837,
%T A037048 946,1060,1184,1308,1449,1592,1744,1903,2076,2240,2432,2618,2818,3028,
%U A037048 3246,3461,3702,3940,4192,4444,4719,4980,5274,5559
%N A037048 Number of pairs {i,j}, i>1, j>1, such that ij < n^2.
%H A037048 Harvey P. Dale, <a href="/A037048/b037048.txt">Table of n, a(n) for n = 2..1000</a>
%F A037048 Sum(floor((n^2-1)/i)+1-i, i=2..n)
%e A037048 f(3)=3 because the only pairs of 2 numbers > 1 that are < 9 are (2,2) (2,3) (2,4).
%t A037048 Table[Sum[Floor[(n^2-1)/i]+1-i,{i,2,n}],{n,2,45}] (* _Harvey P. Dale_, Oct 10 2011 *)
%Y A037048 Cf. A034806, A037092.
%K A037048 nonn
%O A037048 2,2
%A A037048 Joe K. Crump (joecr(AT)carolina.rr.com)