A099170 - OEIS

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A099170

Generalized Motzkin paths with no hills and 3-horizontal steps.

1, 0, 0, 1, 1, 1, 3, 5, 9, 17, 34, 64, 128, 251, 505, 1007, 2044, 4132, 8444, 17243, 35461, 72975, 150910, 312488, 649359, 1351478, 2820366, 5895019, 12348082, 25903960, 54438338, 114563999, 241461037, 509563657, 1076758140 (list; graph; refs; listen; history; internal format)

	OFFSET	`0,7`
	LINKS	`E. Barcucci, E. Pergola, R. Pinzani and S. Rinaldi, ECO method and hill-free generalized Motzkin paths`
	FORMULA	`G.f.: [1-x^3+2x^2-sqrt(1-2x^3+x^6-4x^2)]/[2x^2*(2+x^2-x^3)].`
	CROSSREFS	`Cf. A001003, A089372, A099171.` `Sequence in context: A127904 A048578 A087312 * A018095 A003217 A178717` `Adjacent sequences: A099167 A099168 A099169 * A099171 A099172 A099173`
	KEYWORD	`nonn`
	AUTHOR	`Ralf Stephan, Oct 09 2004`

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Last modified February 17 16:49 EST 2012. Contains 206058 sequences.