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A226710
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Number of n X 1 (-1,0,1) arrays of determinants of 2 X 2 subblocks of some (n+1) X 2 binary array.
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1
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3, 9, 25, 67, 181, 491, 1331, 3607, 9775, 26491, 71793, 194565, 527287, 1428991, 3872683, 10495289, 28443095, 77083123, 208901593, 566140471, 1534287165, 4158044205, 11268641233, 30538943065, 82763043409, 224294643719
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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) = 2*a(n-1) + a(n-2) + 2*a(n-3) + a(n-4) + a(n-5).
Empirical g.f.: x*(3 + 3*x + 4*x^2 + 2*x^3 + x^4) / (1 - 2*x - x^2 - 2*x^3 - x^4 - x^5). - Colin Barker, Sep 06 2018
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EXAMPLE
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Some solutions for n=3:
..0....1....0....1...-1....1...-1...-1....0....0....1....1....0....0....0....1
..1....0...-1...-1...-1....0....0....1...-1....0...-1....0....1....1....0...-1
..1....0....0...-1....0....1....0...-1...-1....1....1...-1...-1....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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