cp's OEIS Frontend

A220999 Number of nX4 arrays of occupancy after each element stays put or moves to some horizontal or vertical neighbor.

%I A220999 #6 Jul 23 2025 01:36:51
%S A220999 21,2989,394580,51672851,6758547145,883809591160,115571009291599,
%T A220999 15112491898694315,1976162121051496204,258409744432367037405,
%U A220999 33790541796768618273627,4418566652828051992947794
%N A220999 Number of nX4 arrays of occupancy after each element stays put or moves to some horizontal or vertical neighbor.
%C A220999 Column 4 of A221001
%H A220999 R. H. Hardin, <a href="/A220999/b220999.txt">Table of n, a(n) for n = 1..19</a>
%e A220999 Some solutions for n=3
%e A220999 ..0..1..1..1....0..4..2..0....0..2..1..2....0..2..1..2....0..2..1..0
%e A220999 ..0..3..1..1....1..0..0..1....1..0..0..3....0..3..0..2....0..3..0..2
%e A220999 ..1..2..0..1....0..2..1..1....1..2..0..0....0..1..0..1....0..1..1..2
%K A220999 nonn
%O A220999 1,1
%A A220999 _R. H. Hardin_ Dec 28 2012