A201374 Number of nX7 0..1 arrays with rows and columns lexicographically nondecreasing read forwards, and nonincreasing read backwards.

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

Author

R. H. Hardin Nov 30 2011

Keywords

• nonn

Comments

Column 7 of A201375

Examples

			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
		

Links

• R. H. Hardin, Table of n, a(n) for n = 1..210

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