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A184038
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1/16 the number of (n+1) X 9 0..3 arrays with all 2 X 2 subblocks having the same four values.
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2
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1225, 1237, 1258, 1300, 1378, 1534, 1834, 2434, 3610, 5962, 10618, 19930, 38458, 75514, 149434, 297274, 592570, 1183162, 2363578, 4724410, 9444538, 18884794, 37762234, 75517114, 151020730, 302027962, 604030138, 1208034490, 2416018618
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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) = 3*a(n-1) - 6*a(n-3) + 4*a(n-4).
G.f.: x*(1225 - 2438*x - 2453*x^2 + 4876*x^3) / ((1 - x)*(1 - 2*x)*(1 - 2*x^2)).
a(n) = 9*2^(n/2-1) + 9*2^(n-1) + 1210 for n even.
a(n) = 9*2^(n-1) + 3*2^((n+1)/2) + 1210 for n odd.
(End)
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EXAMPLE
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Some solutions for 3 X 9:
..3..0..3..1..3..0..3..1..3....0..0..3..1..3..1..0..0..0
..1..1..1..0..1..1..1..0..1....3..1..0..0..0..0..3..1..3
..3..0..3..1..3..0..3..1..3....0..0..3..1..3..1..0..0..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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