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A221900 Number of 3Xn arrays of occupancy after each element stays put or moves to some horizontal, vertical or antidiagonal neighbor, without move-in move-out straight through or left turns.

%I A221900 #6 Jul 23 2025 02:19:26
%S A221900 6,266,7667,236532,7235107,221465158,6778558415,207481075456,
%T A221900 6350624324828,194381582401875,5949680932424079,182109354161412326,
%U A221900 5574049625663873593,170611934699230942606,5222133675326885401935
%N A221900 Number of 3Xn arrays of occupancy after each element stays put or moves to some horizontal, vertical or antidiagonal neighbor, without move-in move-out straight through or left turns.
%C A221900 Row 3 of A221898
%H A221900 R. H. Hardin, <a href="/A221900/b221900.txt">Table of n, a(n) for n = 1..129</a>
%F A221900 Empirical: a(n) = 14*a(n-1) +401*a(n-2) +3090*a(n-3) +7741*a(n-4) -40484*a(n-5) -361940*a(n-6) -1090743*a(n-7) -1171988*a(n-8) +2002414*a(n-9) +720120*a(n-10) -7394610*a(n-11) +17527526*a(n-12) -2069693*a(n-13) -44623518*a(n-14) +78779650*a(n-15) -104778098*a(n-16) +119555094*a(n-17) +11992813*a(n-18) -174397406*a(n-19) +103166505*a(n-20) +131329969*a(n-21) -214551956*a(n-22) +84757573*a(n-23) +13317994*a(n-24) -10733620*a(n-25) +1466700*a(n-26) -21780*a(n-27) -2160*a(n-28)
%e A221900 Some solutions for n=3
%e A221900 ..2..1..0....1..0..1....0..2..0....1..3..2....0..0..1....1..2..2....0..0..4
%e A221900 ..0..1..1....0..1..0....0..3..0....1..0..0....3..0..2....1..0..0....3..0..0
%e A221900 ..1..2..1....3..1..2....2..1..1....0..0..2....0..2..1....1..0..2....0..2..0
%K A221900 nonn
%O A221900 1,1
%A A221900 _R. H. Hardin_ Jan 30 2013