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A224404 Number of n X 3 0..1 arrays with rows unimodal and antidiagonals nondecreasing. 1

%I

%S 7,28,100,358,1288,4636,16684,60040,216064,777544,2798128,10069552,

%T 36237040,130405312,469286272,1688808544,6077472256,21870844480,

%U 78706050496,283237457536,1019279418112,3668054858368,13200135512320

%N Number of n X 3 0..1 arrays with rows unimodal and antidiagonals nondecreasing.

%C Column 3 of A224409.

%H R. H. Hardin, <a href="/A224404/b224404.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.: x*(7 + 2*x^2) / (1 - 4*x + 2*x^2 - 2*x^3). - _Colin Barker_, Aug 30 2018

%e Some solutions for n=3:

%e ..0..1..0....0..0..0....1..1..0....1..1..0....0..0..0....0..1..0....0..0..1

%e ..1..1..0....0..0..0....1..1..1....1..0..0....0..1..0....1..0..0....1..1..0

%e ..1..0..0....0..0..1....1..1..0....0..0..0....1..1..1....0..1..1....1..1..0

%Y Cf. A224409.

%K nonn

%O 1,1

%A _R. H. Hardin_, Apr 05 2013

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Last modified October 1 01:28 EDT 2022. Contains 357134 sequences. (Running on oeis4.)