A027427 - OEIS

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A027427

Number of distinct products ij with 0 <= i < j <= n.

0, 1, 2, 4, 7, 11, 14, 20, 25, 32, 37, 47, 52, 64, 71, 79, 88, 104, 112, 130, 140, 151, 162, 184, 193, 211, 224, 240, 253, 281, 292, 322, 338, 355, 372, 391, 404, 440, 459, 479, 494, 534, 550, 592, 612, 632, 655, 701, 718, 753, 775, 801, 824, 876 (list; graph; refs; listen; history; internal format)

	OFFSET	`0,3`
	LINKS	`T. D. Noe, Table of n, a(n) for n=0..1000`
	FORMULA	`a(n)=A027428(n)+1. - T. D. Noe, Jan 16 2007`
	PROG	`(Haskell)` `import Data.List (nub)` `a027427 n = length $ nub [i*j \| j <- [1..n], i <- [0..j-1]]` `-- Reinhard Zumkeller, Jan 01 2012`
	CROSSREFS	`Cf. A027430, etc.` `Cf. A027384, A027429.` `Sequence in context: A192638 A054850 A167805 * A018385 A087163 A062467` `Adjacent sequences: A027424 A027425 A027426 * A027428 A027429 A027430`
	KEYWORD	`nonn`
	AUTHOR	`N. J. A. Sloane (njas(AT)research.att.com).`

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Last modified February 17 04:58 EST 2012. Contains 205985 sequences.