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 A185552 1/3 the number of n X 2 0..2 arrays with every element equal to exactly one or two of its horizontal and vertical neighbors. 1
 1, 5, 26, 120, 576, 2768, 13256, 63544, 304608, 1460072, 6998680, 33547360, 160805064, 770799288, 3694731616, 17710240936, 84891859544, 406918677600, 1950514582792, 9349551515000, 44815924117856, 214819614744552 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Column 2 of A185559. LINKS R. H. Hardin, Table of n, a(n) for n = 1..200 FORMULA Empirical: a(n) = 3*a(n-1) + 7*a(n-2) + 8*a(n-3) - 8*a(n-5). Empirical g.f.: x*(1 - x)*(1 + 3*x + 7*x^2 + 6*x^3) / (1 - 3*x - 7*x^2 - 8*x^3 + 8*x^5). - Colin Barker, Apr 16 2018 EXAMPLE Some solutions for 4 X 2 with a(1,1)=0! ..0..0....0..2....0..2....0..0....0..0....0..0....0..0....0..0....0..0....0..0 ..2..2....0..2....0..2....0..0....0..1....2..1....2..2....0..1....0..2....1..1 ..1..1....0..2....1..2....2..2....1..1....2..1....1..0....1..1....0..2....2..2 ..2..2....1..1....1..2....2..2....2..2....0..0....1..0....0..0....0..2....0..0 CROSSREFS Cf. A185559. Sequence in context: A293799 A211606 A005499 * A171702 A254825 A272123 Adjacent sequences:  A185549 A185550 A185551 * A185553 A185554 A185555 KEYWORD nonn AUTHOR R. H. Hardin, Jan 31 2011 STATUS approved

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Last modified December 4 13:06 EST 2021. Contains 349526 sequences. (Running on oeis4.)