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.

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

Offset: 1

Author

R. H. Hardin, Jan 25 2016

Keywords

• nonn

Comments

Column 1 of A268073.

Examples

			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
		

Links

• R. H. Hardin, Table of n, a(n) for n = 1..210

Crossrefs

Cf. A268073.

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