A229444 Number of n X 7 0..2 arrays with horizontal differences mod 3 never 1, vertical differences mod 3 never -1, and rows and columns lexicographically nondecreasing.

9, 32, 138, 665, 3184, 14536, 62205, 247607, 914271, 3133068, 9990129, 29755249, 83162347, 219151523, 547116607, 1299869098, 2951439969, 6429248828, 13483439736, 27310437901, 53577074678, 102061137870, 189220453845

Offset: 1

Author

R. H. Hardin, Sep 23 2013

Keywords

• nonn

Comments

Column 7 of A229445.

Examples

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

Links

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

Crossrefs

Cf. A229445.

Formula

Empirical: a(n) = (797/43589145600)*n^14 - (127/1245404160)*n^13 + (1/1451520)*n^12 + (335/19160064)*n^11 - (1381/10886400)*n^10 + (449/322560)*n^9 - (216523/30481920)*n^8 + (653459/8709120)*n^7 - (2384537/4838400)*n^6 + (2642473/870912)*n^5 - (275452937/23950080)*n^4 + (131909609/3991680)*n^3 - (38524939/687960)*n^2 + (21925483/360360)*n - 20.