cp's OEIS Frontend

A221270 Number of n X 2 arrays of occupancy after each element moves to some king-move neighbor, with every occupancy equal to zero or two.

%I A221270 #10 Mar 14 2018 11:20:22
%S A221270 0,6,16,52,174,588,1984,6688,22536,75924,255760,861496,2901696,
%T A221270 9773184,32916280,110861104,373373568,1257492096,4235114944,
%U A221270 14263430416,48037679232,161785483872,544874848384,1835074738624,6180315022560
%N A221270 Number of n X 2 arrays of occupancy after each element moves to some king-move neighbor, with every occupancy equal to zero or two.
%C A221270 Column 2 of A221273.
%H A221270 R. H. Hardin, <a href="/A221270/b221270.txt">Table of n, a(n) for n = 1..65</a>
%F A221270 Empirical: a(n) = 6*a(n-1) - 10*a(n-2) + 4*a(n-3) - 2*a(n-5).
%F A221270 Empirical g.f.: 2*x^2*(1 - x)*(3 - 7*x + x^2) / (1 - 6*x + 10*x^2 - 4*x^3 + 2*x^5). - _Colin Barker_, Mar 14 2018
%e A221270 Some solutions for n=4:
%e A221270 ..0..2....0..0....0..2....2..0....0..2....2..0....0..0....0..2....2..2....0..0
%e A221270 ..2..2....0..2....2..0....2..0....0..2....0..2....2..2....0..2....0..0....2..2
%e A221270 ..0..2....2..0....2..0....0..2....0..2....2..0....0..2....0..0....0..0....2..0
%e A221270 ..0..0....2..2....2..0....2..0....0..2....0..2....2..0....2..2....2..2....2..0
%Y A221270 Cf. A221273.
%K A221270 nonn
%O A221270 1,2
%A A221270 _R. H. Hardin_, Jan 08 2013