A207737 - OEIS

%I #8 Jun 25 2018 12:32:22

%S 9,81,361,1849,10201,58081,335241,1946025,11323225,65950641,384277609,

%T 2239466329,13051920025,76070604481,443368207881,2584130195529,

%U 15061392571801,87784176001041,511643544572521,2982076804476025

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

%C Column 4 of A207741.

%H R. H. Hardin, <a href="/A207737/b207737.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 8*a(n-1) -11*a(n-2) -12*a(n-3) +13*a(n-4) +4*a(n-5) -a(n-6) for n>7.

%F Empirical g.f.: x*(9 + 9*x - 188*x^2 - 40*x^3 + 235*x^4 + 55*x^5 - 16*x^6) / ((1 - x)*(1 + x)*(1 - 6*x + x^2)*(1 - 2*x - x^2)). - _Colin Barker_, Jun 25 2018

%e Some solutions for n=4:

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

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

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

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

%Y Cf. A207741.

%K nonn

%O 1,1

%A _R. H. Hardin_, Feb 19 2012