id:A099018 - OEIS Search Results

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Number of 2 X n 0-1 matrices avoiding simultaneously the right angled numbered polyomino patterns (ranpp) (00;1), (01;0), and (01;1). An occurrence of a ranpp (xy;z) in a matrix A=(a(i,j)) is a triple (a(i1,j1), a(i1,j2), a(i2,j1)) where i1<i2, j1<j2, and these elements are in the same relative order as those in the triple (x,y,z). In general, the number of m X n 0-1 matrices in question is given by g.f. 2xy(y-xy+x-1)/((2x-1)(2y-1)(x+y-1)).

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4, 10, 22, 46, 94, 190, 382, 766, 1534, 3070, 6142, 12286, 24574, 49150, 98302, 196606, 393214, 786430, 1572862, 3145726, 6291454, 12582910, 25165822, 50331646 (list; graph; listen)

	OFFSET	`1,1`
	LINKS	`S. Kitaev, On multi-avoidance of right angled numbered polyomino patterns, Integers: Electronic Journal of Combinatorial Number Theory 4 (2004), A21, 20pp.`
	FORMULA	`G.f.: 2x(2-x)/((1-x)(1-2x))` `3*2^n - 2.`
	CROSSREFS	`Equals A007283(n) - 2.` `Cf. m=3: A005803.` `Sequence in context: A004798 A038621 A078407 this_sequence A033484 A008267 A056112` `Adjacent sequences: A099015 A099016 A099017 this_sequence A099019 A099020 A099021`
	KEYWORD	`nonn`
	AUTHOR	`Sergey Kitaev (kitaev(AT)ms.uky.edu), Nov 13 2004`
	EXTENSIONS	`Corrected by T. D. Noe (noe(AT)sspectra.com), Nov 07 2006`

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Last modified July 24 12:00 EDT 2008. Contains 142294 sequences.

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