A206047 - OEIS

%I #8 Jun 13 2018 08:26:35

%S 48,255,1338,7041,37020,194691,1023822,5384085,28313712,148895799,

%T 783011010,4117687209,21654034308,113873925675,598838568438,

%U 3149163684861,16560776867160,87089576125791,457985415203562

%N Number of (n+1) X 2 0..2 arrays with the number of clockwise edge increases in every 2 X 2 subblock equal to one.

%C Column 1 of A206054.

%H R. H. Hardin, <a href="/A206047/b206047.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 4*a(n-1) +7*a(n-2) -2*a(n-3).

%F Empirical g.f.: 3*x*(16 + 21*x - 6*x^2) / (1 - 4*x - 7*x^2 + 2*x^3). - _Colin Barker_, Jun 13 2018

%e Some solutions for n=4:

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

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

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

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

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

%Y Cf. A206054.

%K nonn

%O 1,1

%A _R. H. Hardin_, Feb 03 2012