A011871 - OEIS

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A011871

[ n(n-1)/18 ].

0, 0, 0, 0, 0, 1, 1, 2, 3, 4, 5, 6, 7, 8, 10, 11, 13, 15, 17, 19, 21, 23, 25, 28, 30, 33, 36, 39, 42, 45, 48, 51, 55, 58, 62, 66, 70, 74, 78, 82, 86, 91, 95, 100, 105, 110, 115, 120, 125, 130, 136, 141, 147, 153, 159, 165, 171, 177, 183, 190, 196, 203, 210, 217, 224, 231, 238 (list; graph; refs; listen; history; internal format)

	OFFSET	`0,8`
	FORMULA	`a(n) = +2a(n-1) -a(n-2) +a(n-9) -2a(n-10) +a(n-11). G.f.: x^5(x^2-x+1) / ( (1-x)^3(1+x+x^2)*(x^6+x^3+1) ). [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Apr 15 2010]`
	CROSSREFS	`Sequence in context: A049810 A132018 A044919 * A130676 A039227 A039273` `Adjacent sequences: A011868 A011869 A011870 * A011872 A011873 A011874`
	KEYWORD	`nonn`
	AUTHOR	`N. J. A. Sloane (njas(AT)research.att.com).`

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Last modified February 16 08:58 EST 2012. Contains 205902 sequences.