A209376 - OEIS

%I #9 Jul 09 2018 16:19:46

%S 8,17,34,80,170,410,882,2138,4610,11186,24130,58562,126338,306626,

%T 661506,1605506,3463682,8406530,18136066,44017154,94961666,230476802,

%U 497225730,1206792194,2603507714,6318845954,13632143362,33085906946,71378829314

%N 1/4 the number of (n+1) X 3 0..2 arrays with every 2 X 2 subblock having distinct edge sums.

%C Column 2 of A209382.

%H R. H. Hardin, <a href="/A209376/b209376.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = a(n-1) + 6*a(n-2) - 6*a(n-3) - 4*a(n-4) + 4*a(n-5).

%F Empirical g.f.: x*(8 + 9*x - 31*x^2 - 8*x^3 + 20*x^4) / ((1 - x)*(1 - 6*x^2 + 4*x^4)). - _Colin Barker_, Jul 09 2018

%e Some solutions for n=4:

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

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

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

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

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

%Y Cf. A209382.

%K nonn

%O 1,1

%A _R. H. Hardin_, Mar 07 2012