A223970 - OEIS

%I #8 Aug 25 2018 16:09:59

%S 22,484,9515,186004,3628696,70779056,1380511272,26926081924,

%T 525177301935,10243271456697,199788923564609,3896764235253108,

%U 76004070829222317,1482414237420454682,28913608801546792225,563942758255071088641

%N Number of n X 3 0..2 arrays with rows and antidiagonals unimodal.

%C Column 3 of A223975.

%H R. H. Hardin, <a href="/A223970/b223970.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 22*a(n-1) - 43*a(n-2) - 125*a(n-3) + 283*a(n-4) - 70*a(n-5) - 111*a(n-6) + 45*a(n-7).

%F Empirical g.f.: x*(22 - 187*x^2 + 236*x^3 + 27*x^4 - 141*x^5 + 45*x^6) / ((1 - x)*(1 - 3*x)*(1 - 18*x - 32*x^2 + 51*x^3 + 17*x^4 - 15*x^5)). - _Colin Barker_, Aug 25 2018

%e Some solutions for n=3:

%e ..1..1..1....2..1..1....0..1..1....1..2..1....0..0..1....2..0..0....1..1..1

%e ..2..2..1....2..1..0....2..1..1....1..2..2....1..2..2....1..1..1....1..2..2

%e ..2..2..0....1..0..0....0..1..2....1..1..0....0..2..2....2..1..0....1..2..2

%Y Cf. A223975.

%K nonn

%O 1,1

%A _R. H. Hardin_, Mar 30 2013