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A231059
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Number of nX4 0..3 arrays x(i,j) with each element horizontally or vertically next to at least one element with value (x(i,j)+1) mod 4, no adjacent elements equal, and upper left element zero
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1
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0, 20, 208, 2376, 27346, 313944, 3607664, 41448458, 476228082, 5471653976, 62867030958, 722316016670, 8299110691962, 95353331221526, 1095570130851502, 12587645301298246, 144626810987686256, 1661701927233901422
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OFFSET
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1,2
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COMMENTS
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LINKS
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FORMULA
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Empirical: a(n) = 19*a(n-1) -87*a(n-2) -96*a(n-3) +1323*a(n-4) -858*a(n-5) -7666*a(n-6) +7362*a(n-7) +27116*a(n-8) -22605*a(n-9) -65782*a(n-10) +30708*a(n-11) +96872*a(n-12) +33216*a(n-13) -97603*a(n-14) -160311*a(n-15) +74945*a(n-16) +167168*a(n-17) +3832*a(n-18) -42520*a(n-19) -66621*a(n-20) -36551*a(n-21) +42655*a(n-22) +26735*a(n-23) -3326*a(n-24) -4386*a(n-25) -3303*a(n-26) -438*a(n-27) +676*a(n-28) +173*a(n-29) -22*a(n-30) -16*a(n-31)
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EXAMPLE
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Some solutions for n=4
..0..1..0..3....0..1..0..1....0..1..2..1....0..3..2..3....0..3..0..1
..3..2..3..2....3..2..1..2....1..2..3..0....1..2..3..0....1..0..3..2
..2..3..0..1....0..1..0..3....0..1..2..1....0..1..2..1....2..1..2..1
..1..2..3..2....3..2..1..0....3..2..3..0....3..2..3..0....3..0..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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