A209729 - OEIS

%I #8 Jul 12 2018 20:26:34

%S 22,124,696,3912,21976,123480,693752,3897880,21900088,123045592,

%T 691329528,3884227224,21823477432,122614931544,688910387576,

%U 3870634114072,21747107494456,122185841630680,686499566270712

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

%C Column 1 of A209736.

%H R. H. Hardin, <a href="/A209729/b209729.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 3*a(n-1) + 14*a(n-2) + 4*a(n-3).

%F Empirical g.f.: 2*x*(11 + 29*x + 8*x^2) / (1 - 3*x - 14*x^2 - 4*x^3). - _Colin Barker_, Jul 12 2018

%e Some solutions for n=4:

%e ..3..1....1..0....1..2....1..3....1..2....0..0....2..1....1..3....1..0....1..1

%e ..2..0....1..3....0..2....0..2....3..3....1..2....2..0....0..2....1..3....3..2

%e ..1..0....2..3....3..2....3..2....1..2....1..3....1..0....3..2....0..2....0..0

%e ..1..3....1..1....3..0....1..0....0..0....0..2....1..3....3..0....1..2....3..1

%e ..0..2....0..3....2..0....1..3....1..3....0..1....2..3....3..1....1..3....2..0

%Y Cf. A209736.

%K nonn

%O 1,1

%A _R. H. Hardin_, Mar 12 2012