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 A267905 Number of n X 1 0..2 arrays with every repeated value in every row unequal to the previous repeated value, and in every column equal to the previous repeated value, and new values introduced in row-major sequential order. 1
 1, 2, 5, 13, 34, 88, 225, 569, 1426, 3548, 8777, 21613, 53026, 129712, 316545, 770993, 1874914, 4553588, 11047625, 26779909, 64869586, 157043368, 380004897, 919150313, 2222499826, 5372538572, 12984354185, 31374801373, 75801065794 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS R. H. Hardin, Table of n, a(n) for n = 1..210 FORMULA Empirical: a(n) = 5*a(n-1) -7*a(n-2) +a(n-3) +2*a(n-4). Conjectures from Colin Barker, Jan 11 2019: (Start) G.f.: x*(1 - 3*x + 2*x^2 + x^3) / ((1 - x)*(1 - 2*x)*(1 - 2*x - x^2)). a(n) = ((1-sqrt(2))^(1+n) + (1+sqrt(2))^(1+n) - 2*(2^n-1)) / 4. (End) EXAMPLE Some solutions for n=8: ..0....0....0....0....0....0....0....0....0....0....0....0....0....0....0....0 ..0....1....1....1....1....1....1....1....1....1....1....1....1....1....1....0 ..1....2....2....0....2....2....2....1....2....0....2....0....2....0....2....0 ..2....2....2....0....1....1....1....1....0....1....0....1....1....0....0....1 ..0....1....2....2....2....1....2....2....0....1....0....2....0....0....0....2 ..1....0....2....0....1....1....1....1....1....1....0....0....2....2....0....1 ..2....2....2....0....2....1....2....0....0....0....1....1....2....0....0....0 ..1....2....2....1....1....1....2....2....2....1....0....1....2....0....2....0 CROSSREFS Column 1 of A267911. Sequence in context: A371426 A027931 A218481 * A209230 A103142 A112844 Adjacent sequences: A267902 A267903 A267904 * A267906 A267907 A267908 KEYWORD nonn AUTHOR R. H. Hardin, Jan 22 2016 STATUS approved

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Last modified September 17 18:03 EDT 2024. Contains 375990 sequences. (Running on oeis4.)