A206311 - OEIS

%I #5 Mar 31 2012 12:37:11

%S 112,873,6831,53463,418468,3275406,25637095,200665376,1570637751,

%T 12293615779,96223962193,753159288558,5895089964664,46141747460483,

%U 361158332020412,2826840073596765,22126098426129671,173184268942327111

%N Number of (n+1)X2 0..3 arrays with the number of clockwise edge increases in every 2X2 subblock equal to two, and every 2X2 determinant nonzero

%C Column 1 of A206318

%H R. H. Hardin, <a href="/A206311/b206311.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 5*a(n-1) +21*a(n-2) +13*a(n-3) -31*a(n-4) -17*a(n-5) +34*a(n-6) +2*a(n-7) -9*a(n-8) -a(n-9)

%e Some solutions for n=4

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

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

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

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

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

%K nonn

%O 1,1

%A _R. H. Hardin_ Feb 06 2012