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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.
2
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
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
KEYWORD
nonn
AUTHOR
R. H. Hardin, Sep 22 2013
STATUS
approved