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A201374
Number of nX7 0..1 arrays with rows and columns lexicographically nondecreasing read forwards, and nonincreasing read backwards
1
2, 8, 44, 280, 2016, 15574, 115168, 728078, 3793342, 16517460, 61759798, 203474642, 603403128, 1638153030, 4126393250, 9747403504, 21778931370, 46349684784, 94496712184, 185448946836, 351735813872, 646956766742, 1157359269036
OFFSET
1,1
COMMENTS
Column 7 of A201375
LINKS
FORMULA
Empirical: a(n) = (1/64864800)*n^14 + (1/831600)*n^13 + (1643/59875200)*n^12 - (247/1995840)*n^11 - (5611/1360800)*n^10 + (61807/1814400)*n^9 + (11951/604800)*n^8 - (31427/30240)*n^7 + (10739983/2721600)*n^6 - (9433741/1814400)*n^5 + (252826879/29937600)*n^4 - (52757143/997920)*n^3 + (1595598461/10810800)*n^2 - (462725/2772)*n + 68
EXAMPLE
Some solutions for n=5
..0..0..0..0..1..1..1....0..1..1..1..1..1..1....0..1..1..1..1..1..1
..0..0..1..1..0..0..1....1..0..1..1..1..1..1....0..1..1..1..1..1..1
..0..0..1..1..0..1..0....1..1..0..0..0..0..1....1..0..0..1..1..1..1
..1..1..0..0..1..0..0....1..1..0..0..0..1..0....1..0..1..0..0..0..0
..1..1..1..1..0..0..0....1..1..1..1..1..0..0....1..1..0..0..0..0..0
CROSSREFS
Sequence in context: A014508 A141147 A346626 * A120928 A286425 A260879
KEYWORD
nonn
AUTHOR
R. H. Hardin Nov 30 2011
STATUS
approved