|
%I #9 Feb 27 2018 07:11:06
%S 1,9,18,30,107,265,553,1505,3852,8922,22477,56889,137617,340401,
%T 851098,2091618,5160851,12817517,31655009,78159377,193558964,
%U 478614470,1182673261,2925763109,7235864705,17887850273,44237338898,109401520982
%N Number of n X 3 binary arrays with every 1 having exactly two king-move neighbors equal to 1.
%C Column 3 of A183450.
%H R. H. Hardin, <a href="/A183444/b183444.txt">Table of n, a(n) for n = 1..200</a>
%F Empirical: a(n) = 2*a(n-1) - a(n-2) + 8*a(n-3) - 7*a(n-4) + 2*a(n-5) - 2*a(n-6).
%F Empirical g.f.: x*(1 + 7*x + x^2 - 5*x^3 - 2*x^5) / (1 - 2*x + x^2 - 8*x^3 + 7*x^4 - 2*x^5 + 2*x^6). - _Colin Barker_, Feb 27 2018
%e Some solutions for 5 X 3:
%e ..0..1..0....1..1..0....0..0..0....0..0..0....1..1..0....0..0..0....0..0..1
%e ..0..1..1....1..0..0....0..1..1....0..1..0....0..1..0....0..0..0....0..1..1
%e ..0..0..0....0..0..0....0..0..1....1..0..1....0..0..0....0..0..0....0..0..0
%e ..0..1..0....0..1..1....1..0..0....1..0..1....1..0..0....1..1..0....1..0..0
%e ..1..1..0....0..0..1....1..1..0....0..1..0....1..1..0....1..0..0....1..1..0
%Y Cf. A183450.
%K nonn
%O 1,2
%A _R. H. Hardin_, Jan 04 2011
| 