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A199642 Number of nX3 0..2 arrays with values 0..2 introduced in row major order and each element equal to one or two horizontal and vertical neighbors.

%I A199642 #7 Jul 22 2025 13:20:53
%S A199642 1,13,112,1265,12748,134748,1396083,14584050,151837464,1582988477,
%T A199642 16494233432,171904221068,1791430664487,18669394073270,
%U A199642 194560012081184,2027588187779377,21130256645906468,220206564513115724
%N A199642 Number of nX3 0..2 arrays with values 0..2 introduced in row major order and each element equal to one or two horizontal and vertical neighbors.
%C A199642 Column 3 of A199647
%H A199642 R. H. Hardin, <a href="/A199642/b199642.txt">Table of n, a(n) for n = 1..200</a>
%F A199642 Empirical: a(n) = 7*a(n-1) +41*a(n-2) -44*a(n-3) -111*a(n-4) -140*a(n-5) +291*a(n-6) -225*a(n-7) +511*a(n-8) +2150*a(n-9) -3007*a(n-10) -6248*a(n-11) -624*a(n-12) +19900*a(n-13) -14308*a(n-14) +15248*a(n-15) -13312*a(n-16) -1648*a(n-17) +21440*a(n-18) -5632*a(n-19) -3968*a(n-20) +5632*a(n-21) -14336*a(n-22) -8192*a(n-23) for n>24
%e A199642 Some solutions for n=4
%e A199642 ..0..1..1....0..0..0....0..0..1....0..1..1....0..0..1....0..0..1....0..1..2
%e A199642 ..0..2..1....0..1..2....2..2..1....0..2..2....1..1..1....1..0..1....0..1..2
%e A199642 ..0..2..0....2..1..2....0..0..1....1..2..2....0..0..2....1..0..0....1..2..2
%e A199642 ..0..2..0....2..1..1....0..0..1....1..1..1....0..0..2....1..2..2....1..0..0
%K A199642 nonn
%O A199642 1,2
%A A199642 _R. H. Hardin_ Nov 08 2011