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A263434
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Number of (n+1) X (1+1) 0..4 arrays with each row and column divisible by 13, read as a base-5 number with top and left being the most significant digits.
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1
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1, 2, 4, 6, 9, 18, 36, 61, 106, 212, 424, 776, 1449, 2898, 5796, 11096, 21486, 42972, 85944, 168421, 331914, 663828, 1327656, 2630981, 5227391, 10454782, 20909564, 41648191, 83053529, 166107058, 332214116, 663226966, 1324747321, 2649494642
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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) = 2*a(n-1) + 9*a(n-4) - 18*a(n-5) - 14*a(n-8) + 28*a(n-9) + a(n-12) - 2*a(n-13).
Empirical g.f.: x*(1 - 2*x^3 - 12*x^4 + 7*x^7 + 25*x^8 - x^11 - 2*x^12) / ((1 - 2*x)*(1 + x^2 - 4*x^4 + x^6)*(1 - x^2 - 4*x^4 - x^6)). - Colin Barker, Jan 01 2019
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EXAMPLE
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All solutions for n=4:
..0..0....2..3....2..3....0..0....0..0....0..0
..0..0....0..0....2..3....2..3....0..0....2..3
..0..0....2..3....2..3....0..0....2..3....2..3
..0..0....0..0....2..3....2..3....0..0....2..3
..0..0....0..0....0..0....0..0....2..3....2..3
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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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