A224033 - OEIS

%I #8 Aug 26 2018 09:50:40

%S 4,13,37,105,298,848,2419,6908,19737,56401,161181,460622,1316360,

%T 3761867,10750568,30722673,87798365,250907593,717036338,2049125344,

%U 5855930115,16734904820,47824518777,136671503209,390575802373,1116176041318

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

%C Column 3 of A224038.

%H R. H. Hardin, <a href="/A224033/b224033.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 4*a(n-1) - 3*a(n-2) - a(n-3) + 2*a(n-5).

%F Empirical g.f.: x*(1 - x)*(4 + x - 2*x^2 - 2*x^3) / (1 - 4*x + 3*x^2 + x^3 - 2*x^5). - _Colin Barker_, Aug 26 2018

%e Some solutions for n=3:

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

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

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

%Y Cf. A224038.

%K nonn

%O 1,1

%A _R. H. Hardin_, Mar 30 2013