id:A103469 - OEIS Search Results

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Number of polyominoes without holes consisting of 3 regular unit n-gons.

+0
13

1, 2, 2, 3, 2, 3, 3, 4, 4, 5, 4, 5, 5, 6, 6, 7, 6, 7, 7, 8, 8, 9, 8, 9, 9, 10, 10, 11, 10, 11, 11, 12, 12, 13, 12, 13, 13, 14, 14, 15, 14, 15, 15, 16, 16, 17, 16, 17, 17, 18, 18, 19, 18, 19, 19, 20, 20, 21, 20, 21, 21, 22, 22, 23, 22, 23, 23, 24, 24, 25, 24, 25, 25, 26, 26, 27, 26, 27 (list; graph; listen)

	OFFSET	`3,2`
	LINKS	`S. Kurz, k-polyominoes.` `M. Koch and S. Kurz, Enumeration of generalized polyominoes`
	FORMULA	`a(n)=[(n-2)/2]-[(n-1)/6]+1`
	EXAMPLE	`a(3)=1 because there is only one polyiamond consisting of 3 triangles and a(4)=2 because there are 2 polyominoes consisting of 3 squares.`
	CROSSREFS	`Cf. A103470, A103471, A103472, A103473.` `Sequence in context: A029213 A029209 A108309 this_sequence A029326 A029204 A057334` `Adjacent sequences: A103466 A103467 A103468 this_sequence A103470 A103471 A103472`
	KEYWORD	`nonn`
	AUTHOR	`Sascha Kurz (sascha.kurz(AT)uni-bayreuth.de), Feb 07 2005`

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

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