A184146 - OEIS

%I #8 Apr 12 2018 06:31:44

%S 499,17203,584143,19882711,676507975,23019453235,783273204631,

%T 26652142523719,906882231446575,30858134866789795,1049997948625823743,

%U 35727878490908505943,1215698852533977865783,41366119750324063746547

%N 1/4 the number of (n+1) X 3 0..3 arrays with every 2 X 2 subblock having at least two equal elements connected horizontally or vertically.

%C Column 2 of A184153.

%H R. H. Hardin, <a href="/A184146/b184146.txt">Table of n, a(n) for n = 1..200</a>

%F Empirical: a(n) = 33*a(n-1) + 53*a(n-2) - 637*a(n-3) + 756*a(n-4).

%F Empirical g.f.: x*(499 + 736*x - 10003*x^2 + 12096*x^3) / (1 - 33*x - 53*x^2 + 637*x^3 - 756*x^4). - _Colin Barker_, Apr 12 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 ..0..2..0....0..0..0....0..0..0....0..0..0....0..3..0....0..2..0....0..0..0

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

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

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

%Y Cf. A184153.

%K nonn

%O 1,1

%A _R. H. Hardin_, Jan 09 2011