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A252721
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.
1
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
OFFSET
1,1
LINKS
FORMULA
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
EXAMPLE
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
CROSSREFS
Row 2 of A252719.
Sequence in context: A199523 A119415 A165866 * A042011 A031064 A183983
KEYWORD
nonn
AUTHOR
R. H. Hardin, Dec 20 2014
STATUS
approved