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A252963
Number of (2+2) X (n+2) 0..4 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
140, 120, 155, 249, 385, 651, 1069, 1757, 2949, 5045, 8293, 14403, 24247, 41597, 70611, 122969, 207079, 362631, 615901, 1073777, 1829085, 3205565, 5445181, 9561243, 16288711, 28558037, 48700563, 85534529, 145725655, 256108431
OFFSET
1,1
LINKS
FORMULA
Empirical: a(n) = a(n-1) + 3*a(n-2) + 2*a(n-3) - 5*a(n-4) - 15*a(n-5) + 9*a(n-6) + 6*a(n-7) + 18*a(n-8) - 18*a(n-9) for n>12.
Empirical g.f.: x*(140 - 20*x - 385*x^2 - 546*x^3 + 131*x^4 + 1909*x^5 + 80*x^6 - 385*x^7 - 2292*x^8 + 906*x^9 + 408*x^10 + 36*x^11) / ((1 - x)*(1 - 3*x^2)*(1 - 2*x^3)*(1 - 3*x^3)). - Colin Barker, Dec 07 2018
EXAMPLE
Some solutions for n=2:
..0..0..1..0....0..1..0..0....0..1..0..0....0..0..1..0....0..0..1..1
..0..2..2..0....2..2..1..1....1..2..1..1....2..0..0..1....2..2..3..3
..0..3..0..0....3..3..2..2....3..3..2..2....3..0..3..3....4..4..0..0
..0..0..3..0....0..0..3..3....0..0..3..3....0..0..2..0....1..1..2..2
CROSSREFS
Row 2 of A252961.
Sequence in context: A183491 A215571 A108317 * A114825 A308617 A353074
KEYWORD
nonn
AUTHOR
R. H. Hardin, Dec 25 2014
STATUS
approved