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A269197
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Number of n X 4 0..3 arrays with some element plus some horizontally, diagonally or antidiagonally adjacent neighbor totalling three no more than once.
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1
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216, 9612, 400428, 15289548, 555862380, 19558138380, 672230393004, 22702294138188, 756261535626732, 24917784636315276, 813662963240248620, 26370904678702613964, 849277413026034547308, 27202597468298860880652
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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) = 62*a(n-1) - 1031*a(n-2) + 2180*a(n-3) - 1535*a(n-4) + 350*a(n-5) - 25*a(n-6) for n>7.
Empirical g.f.: 12*x*(18 - 315*x + 2265*x^2 - 8158*x^3 + 10756*x^4 - 4951*x^5 + 897*x^6) / ((1 - x)^2*(1 - 30*x + 5*x^2)^2). - Colin Barker, Jan 20 2019
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EXAMPLE
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Some solutions for n=2:
..1..0..0..1. .1..3..1..2. .3..1..0..1. .0..2..2..2. .1..0..1..3
..0..1..1..3. .2..3..2..3. .0..1..3..2. .3..2..3..0. .1..1..1..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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