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A210127
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Number of (n+1) X 2 0..3 arrays with every 2 X 2 subblock having one, three or four distinct values, and new values 0..3 introduced in row major order.
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1
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8, 81, 897, 10019, 111993, 1251951, 13995437, 156453699, 1748981553, 19551704471, 218566712277, 2443337243979, 27313843108313, 305338948679391, 3413356121689917, 38157595235947859, 426560259838806273
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OFFSET
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1,1
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COMMENTS
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LINKS
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FORMULA
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Empirical: a(n) = 12*a(n-1) - 9*a(n-2) - 2*a(n-3).
Empirical g.f.: x*(8 - 15*x - 3*x^2) / ((1 - x)*(1 - 11*x - 2*x^2)). - Colin Barker, Jul 14 2018
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EXAMPLE
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Some solutions for n=4:
0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 1 0 0 0 1
0 0 1 2 0 0 0 0 0 0 1 2 2 2 0 2 0 0 1 2
0 0 0 1 0 0 0 0 0 0 3 1 1 0 0 1 1 2 2 3
1 2 1 3 0 0 1 2 1 2 1 0 0 3 1 2 2 0 1 1
3 3 3 0 0 0 1 0 2 0 0 2 0 1 2 3 2 3 0 3
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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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