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A252721
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Number of (2+2) X (n+2) 0..3 arrays with every consecutive three elements in every row and diagonal having exactly two distinct values, and in every column and antidiagonal not having exactly two distinct values, and new values 0 upwards introduced in row major order.
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1
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45, 46, 50, 63, 69, 91, 107, 131, 163, 207, 243, 319, 395, 479, 619, 783, 939, 1231, 1547, 1871, 2443, 3087, 3723, 4879, 6155, 7439, 9739, 12303, 14859, 19471, 24587, 29711, 38923, 49167, 59403, 77839, 98315, 118799, 155659, 196623, 237579, 311311, 393227
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OFFSET
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1,1
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LINKS
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R. H. Hardin, Table of n, a(n) for n = 1..210
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FORMULA
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Empirical: a(n) = a(n-2) + 2*a(n-3) - 2*a(n-5) for n>8.
Empirical g.f.: x*(45 + 46*x + 5*x^2 - 73*x^3 - 73*x^4 + 18*x^5 + 4*x^6 + 2*x^7) / ((1 - x)*(1 + x)*(1 - 2*x^3)). - Colin Barker, Dec 05 2018
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EXAMPLE
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Some solutions for n=4:
..0..1..0..0..2..0....0..0..1..0..0..2....0..1..1..0..1..1....0..0..1..1..2..2
..0..0..1..0..0..2....1..3..3..0..3..3....0..2..0..0..2..0....1..2..2..3..3..0
..0..3..3..0..3..3....2..2..0..0..1..0....0..0..2..0..0..2....3..3..0..0..1..1
..0..1..0..0..1..0....0..0..1..0..0..1....0..3..3..0..3..3....0..1..1..2..2..3
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CROSSREFS
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Row 2 of A252719.
Sequence in context: A199523 A119415 A165866 * A042011 A031064 A183983
Adjacent sequences: A252718 A252719 A252720 * A252722 A252723 A252724
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KEYWORD
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nonn
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AUTHOR
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R. H. Hardin, Dec 20 2014
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STATUS
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approved
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