A011878 - OEIS

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A011878

[ n(n-1)/25 ].

0, 0, 0, 0, 0, 0, 1, 1, 2, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 13, 15, 16, 18, 20, 22, 24, 26, 28, 30, 32, 34, 37, 39, 42, 44, 47, 50, 53, 56, 59, 62, 65, 68, 72, 75, 79, 82, 86, 90, 94, 98, 102, 106, 110, 114, 118, 123, 127 (list; graph; refs; listen; history; internal format)

	OFFSET	`0,9`
	FORMULA	`a(n) = +2a(n-1) -a(n-2) +a(n-25) -2a(n-26) +a(n-27). G.f.: x^6(x^4-x^3+x^2-x+1)(x^4+1)(x^8-x^4+1) / ( (1-x)^3(1+x^4+x^3+x^2+x)*(1+x^20+x^15+x^10+x^5) ). [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Apr 15 2010]`
	CROSSREFS	`Sequence in context: A111633 A034138 A011879 * A017896 A118868 A017885` `Adjacent sequences: A011875 A011876 A011877 * A011879 A011880 A011881`
	KEYWORD	`nonn`
	AUTHOR	`N. J. A. Sloane (njas(AT)research.att.com).`

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Last modified February 17 18:23 EST 2012. Contains 206063 sequences.