A206341 - OEIS

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

%S 880,1589,2030,4711,6090,14181,18258,42351,54654,126861,163842,380391,

%T 491406,1141143,1474206,3423417,4422606,10270239,13267806,30810705,

%U 39803406,92432103,119410206,277296297,358230606,831888879,1074691806

%N Number of (n+1)X7 0..3 arrays with every 2X2 subblock having nonzero determinant and commuting with every horizontal or vertical neighbor

%C Column 6 of A206343

%H R. H. Hardin, <a href="/A206341/b206341.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = a(n-1) +3*a(n-2) -3*a(n-3) for n>15

%e Some solutions for n=4

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

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

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

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

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

%K nonn

%O 1,1

%A _R. H. Hardin_ Feb 06 2012