A206078 - OEIS

%I #8 Jun 13 2018 11:23:56

%S 124,960,7308,55864,426596,3258496,24887884,190093096,1451920276,

%T 11089697360,84702551132,646953877560,4941401481188,37742178485600,

%U 288272879761068,2201813900709576,16817344930171316,128450043128179312

%N Number of (n+1) X 2 0..3 arrays with the number of clockwise edge increases in every 2 X 2 subblock equal to one.

%C Column 1 of A206085.

%H R. H. Hardin, <a href="/A206078/b206078.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 6*a(n-1) +13*a(n-2) -4*a(n-3) +2*a(n-4).

%F Empirical g.f.: 4*x*(31 + 54*x - 16*x^2 + 8*x^3) / (1 - 6*x - 13*x^2 + 4*x^3 - 2*x^4). - _Colin Barker_, Jun 13 2018

%e Some solutions for n=4:

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

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

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

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

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

%Y Cf. A206085.

%K nonn

%O 1,1

%A _R. H. Hardin_, Feb 03 2012