A207730 - OEIS

%I #8 Mar 05 2018 14:47:40

%S 6,36,78,169,611,2209,6016,16384,51840,164025,478305,1394761,4249238,

%T 12945604,38516590,114597025,345332595,1040643081,3114412896,

%U 9320743936,27998628896,84105220081,252138754753,755885919889,2268515874246

%N Number of 3 X n 0..1 arrays avoiding 0 0 0 and 0 1 0 horizontally and 0 1 1 and 1 0 1 vertically.

%C Row 3 of A207729.

%H R. H. Hardin, <a href="/A207730/b207730.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 2*a(n-1) + 5*a(n-3) + 22*a(n-4) - 24*a(n-5) - 15*a(n-6) - 36*a(n-8) + 27*a(n-9).

%F Empirical g.f.: x*(6 + 24*x + 6*x^2 - 17*x^3 - 39*x^4 - 51*x^5 - 9*x^6 - 9*x^7 + 27*x^8) / ((1 - 3*x)*(1 + x - x^2)*(1 + x^2)*(1 + 3*x^2 - 9*x^4)). - _Colin Barker_, Mar 05 2018

%e Some solutions for n=4:

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

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

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

%Y Cf. A207729.

%K nonn

%O 1,1

%A _R. H. Hardin_, Feb 19 2012