|
%I #8 Jun 30 2018 15:11:03
%S 8,54,336,2052,12474,75744,459810,2791152,16942716,102844566,
%T 624279960,3789460422,23002516080,139628253924,847561596858,
%U 5144808733200,31229655752466,189568057623696,1150702676836956,6984914373637974
%N Number of n X 4 0..1 arrays with new values 0..1 introduced in row major order and no element equal to more than one of its immediate leftward or upward neighbors.
%C Column 4 of A208314.
%H R. H. Hardin, <a href="/A208310/b208310.txt">Table of n, a(n) for n = 1..210</a>
%F Empirical: a(n) = 9*a(n-1) - 21*a(n-2) + 21*a(n-3) - 9*a(n-4).
%F Empirical g.f.: 2*x*(4 - 9*x + 9*x^2 - 3*x^3) / (1 - 9*x + 21*x^2 - 21*x^3 + 9*x^4). - _Colin Barker_, Jun 30 2018
%e Some solutions for n=4:
%e ..0..1..1..1....0..0..1..0....0..0..0..1....0..1..0..1....0..1..0..1
%e ..1..0..1..0....1..1..0..1....0..1..1..0....0..0..1..0....0..0..1..0
%e ..1..1..0..1....1..0..1..0....1..0..0..1....1..1..0..1....0..1..0..1
%e ..1..0..1..0....1..0..1..1....0..1..1..0....0..1..1..0....1..0..1..0
%Y Cf. A208314.
%K nonn
%O 1,1
%A _R. H. Hardin_, Feb 25 2012
| 