A229444 - OEIS

%I #6 Mar 15 2023 11:34:03

%S 9,32,138,665,3184,14536,62205,247607,914271,3133068,9990129,29755249,

%T 83162347,219151523,547116607,1299869098,2951439969,6429248828,

%U 13483439736,27310437901,53577074678,102061137870,189220453845

%N 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.

%C Column 7 of A229445.

%H R. H. Hardin, <a href="/A229444/b229444.txt">Table of n, a(n) for n = 1..210</a>

%F 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.

%e Some solutions for n=4

%e ..0..0..0..0..2..2..2....0..0..0..2..2..2..2....0..0..2..2..2..2..2

%e ..0..0..0..0..2..2..2....1..1..1..0..2..2..2....1..1..0..0..2..2..2

%e ..1..1..1..1..0..0..0....1..1..1..1..0..2..2....1..1..1..1..0..0..0

%e ..2..2..2..2..1..1..1....1..1..1..1..1..0..2....2..2..1..1..1..1..1

%Y Cf. A229445.

%K nonn

%O 1,1

%A _R. H. Hardin_, Sep 23 2013