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A205163
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Number of (n+1) X 2 0..3 arrays with every 2 X 2 subblock having unequal diagonal elements or unequal antidiagonal elements, and new values 0..3 introduced in row major order.
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2
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13, 159, 2277, 33831, 506493, 7594479, 113908437, 1708600311, 25628925933, 384433652799, 5766504083397, 86497559125191, 1297463380500573, 19461950688376719, 291929260268255157, 4378938903851640471
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OFFSET
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1,1
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COMMENTS
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LINKS
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FORMULA
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Empirical: a(n) = 18*a(n-1) - 45*a(n-2).
G.f.: x*(13 - 75*x) / ((1 - 3*x)*(1 - 15*x)).
a(n) = 3^(n-1)*(2*5^n+3).
(End)
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EXAMPLE
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Some solutions for n=4:
0 1 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1
0 1 1 1 1 0 0 1 0 1 0 1 0 1 0 1 0 1 0 1
0 0 0 0 0 2 0 2 1 2 0 2 2 0 1 2 2 0 0 0
0 1 0 1 1 3 1 3 1 3 2 1 3 1 0 1 0 1 1 0
1 1 0 0 0 1 2 0 0 0 1 0 1 2 0 0 3 0 2 3
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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