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 A221329 Number of 2 X n arrays of occupancy after each element stays put or moves to some horizontal or antidiagonal neighbor, with no occupancy greater than 2. 1
 1, 17, 119, 866, 6328, 46211, 337274, 2460918, 17953576, 130970758, 955393448, 6969190236, 50836821440, 370827923908, 2704988609708, 19731401249156, 143929610463264, 1049886222652688, 7658333144969252, 55863255070913284 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Row 2 of A221328. LINKS R. H. Hardin, Table of n, a(n) for n = 1..210 FORMULA Empirical: a(n) = 11*a(n-1) - 27*a(n-2) - a(n-3) + 8*a(n-4) - 16*a(n-5) - 6*a(n-6) + 2*a(n-7) for n>9. Empirical g.f.: x*(1 + 6*x - 41*x^2 + 17*x^3 + 24*x^4 - 16*x^5 + x^6 + 5*x^7 - x^8) / (1 - 11*x + 27*x^2 + x^3 - 8*x^4 + 16*x^5 + 6*x^6 - 2*x^7). - Colin Barker, Aug 05 2018 EXAMPLE Some solutions for n=3: ..0..1..0....1..1..1....2..0..1....2..1..0....0..1..1....2..0..2....1..0..1 ..1..2..2....2..0..1....1..0..2....2..1..0....1..1..2....0..1..1....1..1..2 CROSSREFS Cf. A221328. Sequence in context: A048714 A010823 A022709 * A196806 A094944 A274325 Adjacent sequences: A221326 A221327 A221328 * A221330 A221331 A221332 KEYWORD nonn AUTHOR R. H. Hardin, Jan 11 2013 STATUS approved

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Last modified September 19 11:06 EDT 2024. Contains 376010 sequences. (Running on oeis4.)