A229443 Number of nX6 0..2 arrays with horizontal differences mod 3 never 1, vertical differences mod 3 never -1, and rows and columns lexicographically nondecreasing

8, 25, 93, 387, 1609, 6374, 23610, 81177, 258698, 765702, 2113491, 5467941, 13331626, 30795942, 67738085, 142526854, 288060848, 561310955, 1057997269, 1934623043, 3440842683, 5966088386, 10105555904, 16752093179, 27222289586

Offset

1,1

Comments

Column 6 of A229445

Links

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

Formula

Empirical: a(n) = (73/159667200)*n^12 - (19/26611200)*n^11 + (19/2903040)*n^10 + (47/161280)*n^9 - (1259/1612800)*n^8 + (7711/806400)*n^7 - (10715/580608)*n^6 + (30575/96768)*n^5 - (4597853/3628800)*n^4 + (1198483/201600)*n^3 - (621689/55440)*n^2 + (168439/9240)*n - 4

Example

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

Crossrefs

Sequence in context: A041120 A042637 A133661 * A335769 A139026 A135942

Adjacent sequences: A229440 A229441 A229442 * A229444 A229445 A229446

Keyword

nonn

Author

R. H. Hardin Sep 23 2013

Status

approved