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 A238721 Number of n X 3 0..2 arrays with no element equal to the sum modulo 3 of elements to its left or elements above it. 1

%I #11 Sep 30 2023 13:08:16

%S 4,10,40,86,336,704,2704,5660,21504,45176,170464,359400,1350272,

%T 2854496,10694912,22650672,84716224,179637056,671110848,1424180800,

%U 5316817088,11288673952,42124029504,89466980000,333750473152,708999096096,2644373950784,5618300601952

%N Number of n X 3 0..2 arrays with no element equal to the sum modulo 3 of elements to its left or elements above it.

%H R. H. Hardin, <a href="/A238721/b238721.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 17*a(n-2) -96*a(n-4) +210*a(n-6) -152*a(n-8).

%e Some solutions for n=5:

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

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

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

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

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

%Y Column 3 of A238726.

%K nonn

%O 1,1

%A _R. H. Hardin_, Mar 03 2014

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Last modified July 19 13:29 EDT 2024. Contains 374394 sequences. (Running on oeis4.)