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A201619
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Number of nX2 0..3 arrays with rows and columns lexicographically nondecreasing and every element equal to at least one horizontal or vertical neighbor
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1
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4, 16, 56, 211, 718, 2271, 6654, 18191, 46767, 113873, 264247, 587571, 1257743, 2602113, 5220668, 10186777, 19378603, 36016206, 65517188, 116838180, 204546828, 351977489, 595974410, 993932688, 1634127635, 2650699891, 4245165105
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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) = (1/1307674368000)*n^15 - (1/21794572800)*n^14 + (29/9340531200)*n^13 - (19/159667200)*n^12 + (4553/1026432000)*n^11 - (5303/43545600)*n^10 + (2614/893025)*n^9 - (17060387/304819200)*n^8 + (1165550053/1306368000)*n^7 - (165570521/14515200)*n^6 + (11927742139/102643200)*n^5 - (109390684973/119750400)*n^4 + (12109762378249/2270268000)*n^3 - (3278349949289/151351200)*n^2 + (6533366639/120120)*n - 63345 for n>8
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EXAMPLE
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Some solutions for n=9
..0..0....0..1....0..2....0..1....0..3....1..1....0..2....0..2....0..1....0..0
..2..3....0..1....0..2....0..1....0..3....1..1....0..2....0..2....0..1....0..0
..2..3....0..1....0..3....1..1....1..1....1..3....3..0....1..0....0..1....0..1
..2..3....0..2....0..3....2..1....2..0....1..3....3..0....1..0....1..1....0..1
..2..3....2..2....1..2....2..1....2..0....1..3....3..0....1..1....2..0....0..1
..3..0....2..3....1..2....2..1....3..3....1..3....3..2....2..1....2..0....0..3
..3..0....2..3....2..0....2..2....3..3....3..2....3..2....2..1....2..0....0..3
..3..1....3..3....2..0....3..1....3..3....3..2....3..2....2..1....2..0....2..2
..3..1....3..3....2..0....3..1....3..3....3..2....3..2....2..2....2..0....3..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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