A207725 - OEIS

%I #8 Jun 25 2018 12:23:28

%S 9,81,169,441,1225,2809,6241,14161,31329,68121,148225,321489,693889,

%T 1495729,3222025,6932689,14907321,32046921,68873401,147987225,

%U 317944561,683038225,1467273025,3151811881,6770162961,14542189281,31235967169

%N Number of n X 4 0..1 arrays avoiding 0 0 0 and 0 1 0 horizontally and 0 1 1 and 1 0 1 vertically.

%C Column 4 of A207729.

%H R. H. Hardin, <a href="/A207725/b207725.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 3*a(n-1) - 2*a(n-2) + 3*a(n-3) - 6*a(n-4) + 3*a(n-7) + a(n-8) - a(n-10).

%F Empirical g.f.: x*(9 + 54*x - 56*x^2 + 69*x^3 + 51*x^4 - 5*x^5 - 45*x^6 - x^8 - x^9) / ((1 - x)*(1 + x^2 - x^3)*(1 - x - x^3)*(1 - x - 2*x^2 - x^3)). - _Colin Barker_, Jun 25 2018

%e Some solutions for n=4:

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

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

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

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

%Y Cf. A207729.

%K nonn

%O 1,1

%A _R. H. Hardin_, Feb 19 2012