id:A037048 - OEIS Search Results

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

+0
3

0, 3, 9, 20, 33, 54, 77, 108, 142, 186, 228, 285, 342, 409, 481, 563, 644, 742, 837, 946, 1060, 1184, 1308, 1449, 1592, 1744, 1903, 2076, 2240, 2432, 2618, 2818, 3028, 3246, 3461, 3702, 3940, 4192, 4444, 4719, 4980, 5274, 5559 (list; graph; listen)

	OFFSET	`2,2`
	FORMULA	`Sum(floor((n^2-1)/i)+1-i, i=2..n)`
	EXAMPLE	`f(3)=3 because the only pairs of 2 numbers > 1 that are < 9 are (2,2) (2,3) (2,4).`
	CROSSREFS	`Cf. A034806, A037092.` `Sequence in context: A164283 A033315 A073716 this_sequence A139142 A037257 A145068` `Adjacent sequences: A037045 A037046 A037047 this_sequence A037049 A037050 A037051`
	KEYWORD	`nonn`
	AUTHOR	`Joe K. Crump (joecr(AT)carolina.rr.com)`

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Last modified November 30 13:13 EST 2009. Contains 167758 sequences.

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