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 A197211 Number of n X 2 0..4 arrays with each element x equal to the number its horizontal and vertical neighbors equal to 4,3,2,1,0 for x=0,1,2,3,4. 3
 1, 2, 5, 8, 18, 37, 73, 151, 306, 621, 1266, 2572, 5231, 10641, 21637, 44006, 89497, 182008, 370158, 752797, 1530977, 3113587, 6332166, 12877865, 26190002, 53263176, 108322495, 220297841, 448024553, 911157386, 1853040797, 3768569784 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Every 0 is next to 0 4's, every 1 is next to 1 3's, every 2 is next to 2 2's, every 3 is next to 3 1's, every 4 is next to 4 0's. Column 2 of A197217. LINKS R. H. Hardin, Table of n, a(n) for n = 1..200 FORMULA Empirical: a(n) = a(n-1) + a(n-2) + 2*a(n-3) + a(n-5). Empirical g.f.: x*(1 + x + 2*x^2 - x^3 + x^4) / (1 - x - x^2 - 2*x^3 - x^5). - Colin Barker, Feb 22 2018 EXAMPLE All solutions for n=4: ..0..0....2..2....0..0....1..0....0..0....0..0....0..1....0..0 ..0..1....2..2....1..0....3..1....2..2....0..0....1..3....0..0 ..1..3....0..0....3..1....1..0....2..2....2..2....0..1....0..0 ..0..1....0..0....1..0....0..0....0..0....2..2....0..0....0..0 CROSSREFS Cf. A197217. Sequence in context: A304966 A152006 A271619 * A256723 A032063 A320426 Adjacent sequences:  A197208 A197209 A197210 * A197212 A197213 A197214 KEYWORD nonn AUTHOR R. H. Hardin, Oct 11 2011 STATUS approved

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Last modified December 4 11:35 EST 2020. Contains 338923 sequences. (Running on oeis4.)