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A233490
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Number of (n+2) X (1+2) 0..2 arrays with no increasing sequence of length 3 horizontally or antidiagonally downwards.
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1
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16928, 424009, 10619963, 265993633, 6662227346, 166865923720, 4179418541288, 104680086586273, 2621876804023319, 65669013082159633, 1644783337099349594, 41196176081023328236, 1031822785055468622752, 25843618535508922362697
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OFFSET
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1,1
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LINKS
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FORMULA
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Empirical: a(n) = 25*a(n-1) + 2*a(n-2) - 21*a(n-3) + 3*a(n-4).
Empirical g.f.: x*(16928 + 809*x - 14118*x^2 + 2028*x^3) / ((1 + x)*(1 - 26*x + 24*x^2 - 3*x^3)). - Colin Barker, Oct 11 2018
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EXAMPLE
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Some solutions for n=1:
..2..2..2....1..2..2....0..1..1....0..2..0....1..1..0....2..2..2....2..0..1
..1..2..1....2..0..1....2..0..1....1..0..1....2..2..0....1..0..1....1..0..0
..2..0..0....0..1..0....0..2..2....0..0..1....1..2..1....0..0..0....1..2..0
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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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