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A252956
Number of (n+2) X (3+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
223, 155, 259, 443, 871, 1681, 2999, 6103, 11983, 21749, 44515, 88087, 161123, 330817, 656011, 1210571, 2483599, 4939057, 9174815, 18819943, 37462903, 70101461, 143554507, 286165735, 538738571, 1101824353, 2197577587, 4162662491
OFFSET
1,1
LINKS
FORMULA
Empirical: a(n) = 4*a(n-1) - 2*a(n-2) - 3*a(n-3) - 13*a(n-4) + 8*a(n-5) + 70*a(n-6) - 105*a(n-7) + 42*a(n-8) for n>10.
Empirical g.f.: x*(223 - 737*x + 85*x^2 + 386*x^3 + 2981*x^4 + 91*x^5 - 14137*x^6 + 16334*x^7 - 4830*x^8 - 420*x^9) / ((1 - x)^2*(1 - 2*x)*(1 - 3*x^2)*(1 - 7*x^3)). - Colin Barker, Dec 07 2018
EXAMPLE
Some solutions for n=2:
..0..1..1..2..2....0..1..1..2..2....0..1..1..0..1....0..1..1..2..2
..3..0..0..1..1....3..0..0..4..4....0..2..0..0..2....3..0..0..1..1
..2..4..4..0..4....2..3..3..1..1....0..0..2..0..0....2..3..3..0..0
..1..3..3..4..3....4..2..2..0..0....0..1..1..0..1....1..4..4..3..3
CROSSREFS
Column 3 of A252961.
Sequence in context: A268017 A267978 A234623 * A163653 A178551 A105982
KEYWORD
nonn
AUTHOR
R. H. Hardin, Dec 25 2014
STATUS
approved