A184369 - OEIS

%I #8 Feb 27 2018 08:59:05

%S 153,2755,49235,880781,15754461,281803871,5040682279,90163722073,

%T 1612776998193,28848073268443,516011408652059,9230001997285733,

%U 165098940527912805,2953158641948611223,52823754874667184367

%N 1/3 the number of (n+1) X 3 0..2 arrays with every 2 X 2 subblock having at least two equal elements connected horizontally or vertically.

%C Column 2 of A184376.

%H R. H. Hardin, <a href="/A184369/b184369.txt">Table of n, a(n) for n = 1..200</a>

%F Empirical: a(n) = 17*a(n-1) + 19*a(n-2) - 57*a(n-3) + 18*a(n-4).

%F Empirical g.f.: x*(153 + 154*x - 507*x^2 + 162*x^3) / (1 - 17*x - 19*x^2 + 57*x^3 - 18*x^4). - _Colin Barker_, Feb 27 2018

%e Some solutions for 5 X 3 with a(1,1)=0:

%e ..0..0..0....0..0..0....0..0..0....0..0..0....0..0..0....0..0..0....0..0..0

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

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

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

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

%Y Cf. A184376.

%K nonn

%O 1,1

%A _R. H. Hardin_, Jan 12 2011