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

1,1

Comments

Column 7 of A229445.

Links

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

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.

Example

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

Crossrefs

Cf. A229445.

Sequence in context: A367669 A231999 A297298 * A300773 A317279 A196016

Adjacent sequences: A229441 A229442 A229443 * A229445 A229446 A229447

Keyword

nonn

Author

R. H. Hardin, Sep 23 2013

Status

approved