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A265992
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Number of 2 X n integer arrays with each element equal to the number of horizontal and antidiagonal neighbors not equal to itself.
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1
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1, 1, 2, 2, 4, 6, 7, 11, 15, 26, 48, 82, 135, 227, 375, 634, 1088, 1850, 3135, 5315, 8983, 15218, 25832, 43818, 74319, 126027, 213615, 362162, 614120, 1041346, 1765847, 2994267, 5076959, 8608474, 14596640, 24750370, 41967671, 71161491, 120662599
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OFFSET
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1,3
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LINKS
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FORMULA
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Empirical: a(n) = 3*a(n-3) + a(n-4) + 2*a(n-5) + 2*a(n-6) + 3*a(n-7) + 2*a(n-8) - 4*a(n-9) - 4*a(n-10) - 4*a(n-11) for n>14.
Empirical g.f.: x*(1 + x + 2*x^2 - x^3 - 3*x^5 - 5*x^6 - 12*x^7 - 20*x^8 - 17*x^9 - 14*x^10 + 4*x^13) / ((1 - x)*(1 + x)*(1 + x + x^2)*(1 - x - 2*x^3)*(1 + x^2 + 2*x^4)). - Colin Barker, Jan 09 2019
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EXAMPLE
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Some solutions for n=6:
..1..3..2..2..1..1....1..3..1..1..1..1....1..2..2..1..1..1....0..0..0..0..0..0
..1..1..1..1..3..1....1..1..3..2..2..1....1..1..1..2..2..1....0..0..0..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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