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%I #9 Feb 26 2018 08:21:57
%S 1,2,4,12,39,138,499,1830,6723,24714,90751,332910,1219947,4466562,
%T 16340935,59746326,218334531,797537226,2912254303,10631252766,
%U 38800597851,141582417426,516549545527,1884336977574,6873201390579
%N 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.
%C Column 1 of A268073.
%H R. H. Hardin, <a href="/A268069/b268069.txt">Table of n, a(n) for n = 1..210</a>
%F 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.
%F 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
%e Some solutions for n=7:
%e ..0....0....0....0....0....0....0....0....0....0....0....0....0....0....0....0
%e ..1....1....0....1....1....1....0....1....1....1....1....1....1....1....0....1
%e ..2....1....1....2....2....1....1....2....1....0....0....2....2....1....1....2
%e ..3....0....1....1....0....0....1....3....2....2....1....0....3....2....2....1
%e ..3....0....0....3....1....0....0....3....1....1....0....0....3....1....3....2
%e ..1....2....2....3....2....2....0....0....3....1....2....1....0....3....3....0
%e ..3....3....3....1....2....0....2....2....1....3....1....3....3....0....1....0
%Y Cf. A268073.
%K nonn
%O 1,2
%A _R. H. Hardin_, Jan 25 2016
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