

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 rowmajor 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
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OFFSET

1,2


LINKS



FORMULA

Empirical: a(n) = 5*a(n1) 7*a(n2) +a(n3) +2*a(n4).
G.f.: x*(1  3*x + 2*x^2 + x^3) / ((1  x)*(1  2*x)*(1  2*x  x^2)).
a(n) = ((1sqrt(2))^(1+n) + (1+sqrt(2))^(1+n)  2*(2^n1)) / 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



KEYWORD

nonn


AUTHOR



STATUS

approved



