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A281206
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Number of 2 X n 0..1 arrays with no element equal to more than one of its horizontal and antidiagonal neighbors, with the exception of exactly one element, and with new values introduced in order 0 sequentially upwards.
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1
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0, 2, 14, 28, 52, 94, 166, 290, 502, 864, 1480, 2526, 4298, 7294, 12350, 20868, 35196, 59262, 99630, 167258, 280422, 469576, 785424, 1312318, 2190482, 3652854, 6086126, 10131820, 16853572, 28013854, 46531510, 77237906, 128126038, 212413104
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OFFSET
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1,2
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LINKS
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FORMULA
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Empirical: a(n) = 3*a(n-1) - a(n-2) - 3*a(n-3) + a(n-4) + a(n-5) for n>7.
Empirical g.f.: 2*x^2*(1 + 4*x - 6*x^2 - 6*x^3 + 3*x^4 + 2*x^5) / ((1 - x)*(1 - x - x^2)^2). - Colin Barker, Feb 18 2019
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EXAMPLE
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Some solutions for n=4:
..0..0..1..0. .0..1..0..0. .0..0..0..1. .0..0..1..1. .0..0..1..0
..0..1..0..1. .0..1..1..1. .0..1..0..0. .1..0..1..0. .1..1..0..1
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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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