A011880 - OEIS

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A011880

[ n(n-1)/27 ].

0, 0, 0, 0, 0, 0, 1, 1, 2, 2, 3, 4, 4, 5, 6, 7, 8, 10, 11, 12, 14, 15, 17, 18, 20, 22, 24, 26, 28, 30, 32, 34, 36, 39, 41, 44, 46, 49, 52, 54, 57, 60, 63, 66, 70, 73, 76, 80, 83, 87, 90, 94, 98, 102, 106, 110, 114, 118, 122, 126, 131, 135, 140, 144, 149, 154, 158, 163, 168, 173 (list; graph; refs; listen; history; internal format)

	OFFSET	`0,9`
	FORMULA	`G.f.: x^6(1-x^3+x^5+x^11-x^13+x^16)(1-x^6)/((1-x)(1-x^2)(1-x^3)(1-x^27)).`
	MATHEMATICA	`Table[Floor[n*(n+1)/27], {n, 5!}] [From Vladimir Orlovsky (4vladimir(AT)gmail.com), Mar 14 2010]`
	PROG	`(PARI) a(n)=(n^2-n)\27`
	CROSSREFS	`Sequence in context: A008672 A097923 A027582 * A029044 A029043 A097920` `Adjacent sequences: A011877 A011878 A011879 * A011881 A011882 A011883`
	KEYWORD	`nonn`
	AUTHOR	`N. J. A. Sloane (njas(AT)research.att.com).`
	EXTENSIONS	`Mathematica program [From Vladimir Orlovsky (4vladimir(AT)gmail.com), Mar 14 2010]`

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Last modified February 16 09:27 EST 2012. Contains 205904 sequences.