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A235556
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Number of (n+1)X(1+1) 0..3 arrays with the sum of each 2X2 subblock two extreme terms minus its two median terms lexicographically nondecreasing rowwise and columnwise
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2
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256, 2612, 23024, 180640, 1321956, 9182760, 61590128, 402719344, 2587649440, 16427598848, 103462837312, 648431897408, 4052631770944, 25299606268544, 157920835375104, 986393232739328, 6167644453234432, 38615919748243968
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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) = 20*a(n-1) -76*a(n-2) -996*a(n-3) +8480*a(n-4) +8424*a(n-5) -279280*a(n-6) +457552*a(n-7) +4597088*a(n-8) -15344288*a(n-9) -40904192*a(n-10) +233024064*a(n-11) +149002944*a(n-12) -2177686656*a(n-13) +809190144*a(n-14) +13696091136*a(n-15) -14371325184*a(n-16) -59950127104*a(n-17) +97895484416*a(n-18) +183101051904*a(n-19) -419660306432*a(n-20) -377096103936*a(n-21) +1250719469568*a(n-22) +458326937600*a(n-23) -2681697173504*a(n-24) -102179840000*a(n-25) +4178539053056*a(n-26) -732985442304*a(n-27) -4711370539008*a(n-28) +1477085659136*a(n-29) +3778314698752*a(n-30) -1487068856320*a(n-31) -2083824599040*a(n-32) +874816471040*a(n-33) +743786414080*a(n-34) -286051532800*a(n-35) -152672665600*a(n-36) +40265318400*a(n-37) +13421772800*a(n-38)
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EXAMPLE
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Some solutions for n=4
..2..2....2..2....2..0....2..2....0..2....0..3....0..2....2..3....0..3....2..0
..0..0....2..1....3..3....1..3....2..2....3..0....3..3....3..0....2..1....2..1
..2..2....0..3....1..3....2..2....3..1....2..1....0..1....1..3....0..0....1..0
..1..3....1..2....0..3....1..1....0..2....0..0....3..0....0..2....2..1....2..3
..1..3....1..0....2..0....3..1....1..1....3..2....0..1....3..1....1..1....2..2
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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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