A229426 Number of n X 6 0..2 arrays with horizontal differences mod 3 never 1, vertical differences mod 3 never -1, rows lexicographically nondecreasing, and columns lexicographically nonincreasing.

23, 175, 1116, 5700, 24126, 87648, 281016, 812352, 2152643, 5297329, 12231874, 26724490, 55625600, 110928984, 212948248, 395089316, 710860767, 1243965435, 2122565928, 3539121568, 5777563514, 9250018192, 14545817232, 22496156480

Offset

1,1

Comments

Column 6 of A229428.

Links

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

Formula

Empirical: a(n) = (1/11404800)*n^12 + (1/211200)*n^11 + (37/345600)*n^10 + (143/103680)*n^9 + (27977/2419200)*n^8 + (83399/1209600)*n^7 + (321133/1036800)*n^6 + (35291/34560)*n^5 + (66941/28800)*n^4 + (614843/129600)*n^3 + (149511/30800)*n^2 + (19627/3465)*n + 4.

Example

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

Crossrefs

Cf. A229428.

Sequence in context: A155842 A248698 A186260 * A274587 A302200 A269072

Adjacent sequences: A229423 A229424 A229425 * A229427 A229428 A229429

Keyword

nonn

Author

R. H. Hardin, Sep 22 2013

Status

approved