|
%I
%S 4,16,61,232,882,3353,12747,48460,184229,700378,2662606,10122349,
%T 38481829,146295209,556166085,2114359836,8038098037,30558194945,
%U 116172168341,441648229594,1679000758004,6383006556982,24266083569200
%N Number of n X 1 0..3 arrays avoiding the pattern z-1 z-1 z in any row, column or nw-to-se diagonal.
%C Column 1 of A206577.
%H R. H. Hardin, <a href="/A206570/b206570.txt">Table of n, a(n) for n = 1..210</a>
%F Empirical: a(n) = 4*a(n-1) - 3*a(n-3) + 2*a(n-5) - a(n-7).
%F Empirical g.f.: x*(4 - 3*x^2 + 2*x^4 - x^6) / (1 - 4*x + 3*x^3 - 2*x^5 + x^7). - _Colin Barker_, Feb 20 2018
%e Some solutions for n=4:
%e ..1....1....2....0....0....1....0....3....0....1....1....0....1....2....1....1
%e ..0....3....0....2....1....3....2....0....0....0....1....3....3....0....0....3
%e ..0....2....1....2....1....0....1....3....2....1....0....1....3....1....1....2
%e ..0....1....2....1....3....1....3....1....0....3....3....2....1....0....1....2
%Y Cf. A206577.
%K nonn
%O 1,1
%A _R. H. Hardin_, Feb 09 2012
| 