id:A102620 - OEIS Search Results

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Number of legal Go positions on a 1 X n board (for which 3^n is a trivial upper bound).

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1, 5, 15, 41, 113, 313, 867, 2401, 6649, 18413, 50991, 141209, 391049, 1082929, 2998947, 8304961, 22998865, 63690581 (list; graph; listen)

	OFFSET	`1,2`
	LINKS	`Author?, The Logical Rules of Go`
	FORMULA	`For n >= 4, a(n) = 3*a(n-1) - a(n-2) + a(n-3).`
	EXAMPLE	`a(2)=5 because .. .O .S O. S. are the 5 legal 1 X 2 Go positions, while OO OS SO SS are all illegal, having stones without liberties.`
	CROSSREFS	`Cf. A094777.` `Cf. A030236, A098182.` `Sequence in context: A038066 A113861 A080870 this_sequence A053731 A111295 A032193` `Adjacent sequences: A102617 A102618 A102619 this_sequence A102621 A102622 A102623`
	KEYWORD	`nonn`
	AUTHOR	`John Tromp (tromp(AT)cwi.nl), Jan 31 2005`

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Last modified November 25 20:09 EST 2009. Contains 167514 sequences.