A229427 Number of nX7 0..2 arrays with horizontal differences mod 3 never 1, vertical differences mod 3 never -1, rows lexicographically nondecreasing, and columns lexicographically nonincreasing.

30, 282, 2187, 13345, 66503, 281016, 1037193, 3420692, 10260128, 28379127, 73192023, 177601008, 408454945, 895812869, 1883191437, 3811219431, 7453126082, 14128822736, 26035706883, 46749593643, 81969420795, 140605855270

Offset: 1

Author

R. H. Hardin Sep 22 2013

Keywords

• nonn

Comments

Column 7 of A229428

Examples

			Some solutions for n=4
..1..1..0..0..0..0..0....1..1..1..1..0..0..0....1..1..0..0..0..0..0
..1..1..0..0..0..0..0....2..1..1..1..0..0..0....1..1..1..1..0..0..0
..1..1..0..0..0..0..0....2..2..2..1..1..0..0....2..2..1..1..1..1..1
..1..1..0..0..0..0..0....2..2..2..1..1..0..0....2..2..2..2..2..2..1
		

Links

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

Formula

Empirical: a(n) = (1/660441600)*n^14 + (1/9434880)*n^13 + (1/311850)*n^12 + (283/4989600)*n^11 + (23/34560)*n^10 + (5/896)*n^9 + (55843/1587600)*n^8 + (154153/907200)*n^7 + (4503127/7257600)*n^6 + (1244953/725760)*n^5 + (56059/14400)*n^4 + (1646347/302400)*n^3 + (401116003/50450400)*n^2 + (124079/24024)*n + 5