A081757 - OEIS

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A081757

Number of ways to write n as i*j+i-j, 0<i<j.

0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 2, 1, 2, 1, 2, 1, 2, 1, 3, 1, 2, 2, 2, 1, 3, 1, 2, 2, 3, 1, 3, 1, 3, 2, 2, 1, 4, 1, 2, 2, 4, 1, 3, 1, 3, 3, 2, 1, 4, 1, 3, 2, 3, 1, 4, 2, 3, 2, 2, 1, 6, 1, 2, 2, 3, 2, 4, 1, 3, 2, 4, 1, 5, 1, 2, 3, 3, 2, 4, 1, 4, 2, 2, 1, 6, 2, 2, 2, 4, 1, 5, 2, 3, 2, 2, 2, 6, 1, 3, 2, 4, 1, 4, 1, 4 (list; graph; refs; listen; history; internal format)

	OFFSET	`1,11`
	FORMULA	`G.f.: Sum(x^(n^2+3*n)/(1-x^n),n = 1 .. infinity). - Vladeta Jovovic (vladeta(AT)eunet.rs), May 13 2008`
	EXAMPLE	`n=25 = 223+2-23 = 311+3-11 = 4*7+4-7, therefore a(25)=3.`
	CROSSREFS	`Cf. A072670.` `Sequence in context: A160979 A167679 A051881 * A033107 A083897 A025823` `Adjacent sequences: A081754 A081755 A081756 * A081758 A081759 A081760`
	KEYWORD	`nonn`
	AUTHOR	`Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Apr 08 2003`

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Last modified February 15 18:22 EST 2012. Contains 205835 sequences.