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

1,1

Comments

Column 7 of A229428

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

Example

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

Crossrefs

Sequence in context: A214944 A259455 A270852 * A113754 A129029 A101381

Adjacent sequences: A229424 A229425 A229426 * A229428 A229429 A229430

Keyword

nonn

Author

R. H. Hardin Sep 22 2013

Status

approved