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%I #10 Aug 27 2018 06:04:13
%S 4,16,58,208,748,2692,9688,34864,125464,451504,1624816,5847184,
%T 21042112,75723712,272504992,980656768,3529064512,12699954496,
%U 45703002496,164470230016,591874824064,2129964841216,7665050176768,27584020672768
%N Number of n X 3 0..1 arrays with rows nondecreasing and antidiagonals unimodal.
%C Column 3 of A224133.
%H R. H. Hardin, <a href="/A224128/b224128.txt">Table of n, a(n) for n = 1..210</a>
%F Empirical: a(n) = 4*a(n-1) - 2*a(n-2) + 2*a(n-3).
%F Empirical g.f.: 2*x*(2 + x^2) / (1 - 4*x + 2*x^2 - 2*x^3). - _Colin Barker_, Aug 27 2018
%e Some solutions for n=3:
%e ..0..0..0....1..1..1....1..1..1....0..1..1....0..0..1....0..0..1....0..0..1
%e ..1..1..1....0..0..1....0..1..1....0..0..0....0..1..1....1..1..1....0..0..0
%e ..0..0..0....0..0..1....0..1..1....0..0..1....0..0..1....0..0..1....0..1..1
%Y Cf. A224133.
%K nonn
%O 1,1
%A _R. H. Hardin_, Mar 31 2013
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