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

Author

R. H. Hardin, Sep 22 2013

Keywords

• nonn

Comments

Column 6 of A229428.

Examples

			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
		

Links

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

Crossrefs

Cf. A229428.

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.