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 A268069 Number of n X 1 0..3 arrays with every repeated value in every row and column unequal to the previous repeated value, and new values introduced in row-major sequential order. 3
 1, 2, 4, 12, 39, 138, 499, 1830, 6723, 24714, 90751, 332910, 1219947, 4466562, 16340935, 59746326, 218334531, 797537226, 2912254303, 10631252766, 38800597851, 141582417426, 516549545527, 1884336977574, 6873201390579 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Column 1 of A268073. LINKS R. H. Hardin, Table of n, a(n) for n = 1..210 FORMULA Empirical: a(n) = 6*a(n-1) - 3*a(n-2) - 30*a(n-3) + 28*a(n-4) + 36*a(n-5) - 36*a(n-6) for n>8. Empirical g.f.: x*(1 - 4*x - 5*x^2 + 24*x^3 + 11*x^4 - 32*x^5 + 12*x^7) / ((1 - x)*(1 - 3*x)*(1 - 2*x^2)*(1 - 2*x - 6*x^2)). - Colin Barker, Feb 26 2018 EXAMPLE Some solutions for n=7: ..0....0....0....0....0....0....0....0....0....0....0....0....0....0....0....0 ..1....1....0....1....1....1....0....1....1....1....1....1....1....1....0....1 ..2....1....1....2....2....1....1....2....1....0....0....2....2....1....1....2 ..3....0....1....1....0....0....1....3....2....2....1....0....3....2....2....1 ..3....0....0....3....1....0....0....3....1....1....0....0....3....1....3....2 ..1....2....2....3....2....2....0....0....3....1....2....1....0....3....3....0 ..3....3....3....1....2....0....2....2....1....3....1....3....3....0....1....0 CROSSREFS Cf. A268073. Sequence in context: A341240 A108532 A213058 * A215071 A180487 A000940 Adjacent sequences:  A268066 A268067 A268068 * A268070 A268071 A268072 KEYWORD nonn AUTHOR R. H. Hardin, Jan 25 2016 STATUS approved

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Last modified May 9 10:21 EDT 2021. Contains 343732 sequences. (Running on oeis4.)