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A208390 Number of nX6 0..2 arrays with new values 0..2 introduced in row major order and no element equal to more than two of its immediate leftward or upward or right-upward antidiagonal neighbors.

%I A208390 #7 Jul 22 2025 21:19:11
%S A208390 122,76806,48890520,31112194860,19798894881900,12599441934740388,
%T A208390 8017919094401985204,5102370957264743298996,3247000759052439181788564,
%U A208390 2066297024969543787823082196,1314931443577477050291551747028
%N A208390 Number of nX6 0..2 arrays with new values 0..2 introduced in row major order and no element equal to more than two of its immediate leftward or upward or right-upward antidiagonal neighbors.
%C A208390 Column 6 of A208392
%H A208390 R. H. Hardin, <a href="/A208390/b208390.txt">Table of n, a(n) for n = 1..210</a>
%F A208390 Empirical: a(n) = 649*a(n-1) -8088*a(n-2) +32724*a(n-3) -69156*a(n-4) +80352*a(n-5) -46656*a(n-6) for n>7
%e A208390 Some solutions for n=4
%e A208390 ..0..0..0..1..2..1....0..0..0..0..1..0....0..0..0..0..0..1....0..0..1..2..0..2
%e A208390 ..0..2..2..0..0..2....0..1..2..1..0..0....1..2..0..1..2..1....2..0..2..2..0..1
%e A208390 ..1..0..1..2..0..2....2..0..0..0..2..0....2..2..0..0..0..2....2..1..2..1..2..1
%e A208390 ..0..2..2..2..0..2....0..1..1..1..0..1....2..0..1..1..0..1....0..2..1..1..1..2
%K A208390 nonn
%O A208390 1,1
%A A208390 _R. H. Hardin_ Feb 25 2012