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A227253
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Number of nX3 binary arrays indicating whether each 2X2 subblock of a larger binary array has lexicographically nondecreasing rows and columns, for some larger (n+1)X4 binary array with rows and columns of the latter in lexicographically nondecreasing order
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1
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4, 9, 36, 134, 450, 1353, 3722, 9529, 22957, 52447, 114282, 238618, 479284, 929223, 1744166, 3178057, 5634919, 9743313, 16461342, 27222342, 44134038, 70247085, 109912626, 169252849, 256773585, 384153835, 567253826, 827390858, 1192940904
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OFFSET
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1,1
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COMMENTS
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LINKS
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FORMULA
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Empirical: a(n) = (1/9979200)*n^11 - (1/453600)*n^10 + (1/11340)*n^9 - (71/60480)*n^8 + (163/11200)*n^7 - (251/2700)*n^6 + (49501/90720)*n^5 - (319397/181440)*n^4 + (486707/113400)*n^3 + (34133/25200)*n^2 - (238061/6930)*n + 65 for n>3
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EXAMPLE
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Some solutions for n=4
..1..1..1....1..1..1....1..1..1....1..0..0....1..1..1....1..1..0....1..0..0
..1..0..0....1..0..0....1..1..0....0..1..1....1..1..0....1..0..1....0..1..1
..0..1..1....0..1..1....1..0..1....0..1..0....1..1..0....1..0..0....1..1..0
..1..1..0....1..1..1....0..0..1....1..1..0....1..0..0....1..0..0....1..1..1
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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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