A206048 - OEIS

%I #8 Jun 13 2018 08:25:51

%S 255,2310,20400,180195,1590378,14037225,123893883,1093502865,

%T 9651382368,85184227872,751845910863,6635879577384,58569045932253,

%U 516937220242281,4562548107080751,40269580936702038,355424011046747292

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

%C Column 2 of A206054.

%H R. H. Hardin, <a href="/A206048/b206048.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 9*a(n-1) + a(n-2) - 24*a(n-3) + 15*a(n-4) - 6*a(n-5) + 4*a(n-6).

%F Empirical g.f.: 3*x*(85 + 5*x - 215*x^2 + 135*x^3 - 54*x^4 + 36*x^5) / (1 - 9*x - x^2 + 24*x^3 - 15*x^4 + 6*x^5 - 4*x^6). - _Colin Barker_, Jun 13 2018

%e Some solutions for n=4:

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

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

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

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

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

%Y Cf. A206054.

%K nonn

%O 1,1

%A _R. H. Hardin_, Feb 03 2012