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A212925 Number of n X 3 0..2 arrays with no column j greater than column j-1 in all rows.

%I A212925 #11 Jul 21 2018 15:52:19
%S A212925 10,568,18226,518320,14230810,386357608,10450787266,282343443040,
%T A212925 7624822644010,205884158525848,5558997804436306,150094070437926160,
%U A212925 4052550069287319610,109418943377927449288,2954312294768569509346
%N A212925 Number of n X 3 0..2 arrays with no column j greater than column j-1 in all rows.
%C A212925 Column 3 of A212930.
%H A212925 R. H. Hardin, <a href="/A212925/b212925.txt">Table of n, a(n) for n = 1..210</a>
%F A212925 Empirical: a(n) = 37*a(n-1) -279*a(n-2) +243*a(n-3).
%F A212925 Explicit formula: a(n) = 27^n - 2*9^n + 1. - _Vaclav Kotesovec_, May 31 2012
%F A212925 Empirical g.f.: 2*x*(5 + 99*x) / ((1 - x)*(1 - 9*x)*(1 - 27*x)). - _Colin Barker_, Jul 21 2018
%e A212925 Some solutions for n=3:
%e A212925 ..2..2..2....0..1..1....1..2..1....1..0..1....0..0..0....2..1..2....2..1..0
%e A212925 ..0..0..2....0..0..2....2..1..2....1..2..2....1..2..0....1..2..2....2..1..2
%e A212925 ..1..2..0....0..0..2....1..0..2....2..1..2....1..2..2....1..2..0....2..1..1
%Y A212925 Cf. A212930.
%K A212925 nonn
%O A212925 1,1
%A A212925 _R. H. Hardin_, May 31 2012