%I #6 Apr 10 2022 14:32:44
%S 21,3605,544757,81980587,12325049264,1852447247829,278394265759168,
%T 41836968289680535,6287169859547251975,944818763789937611918,
%U 141984605326159531366196,21337022505681038084244109
%N Number of n X 4 arrays of occupancy after each element stays put or moves to some horizontal, diagonal or antidiagonal neighbor.
%C Column 4 of A221723.
%H R. H. Hardin, <a href="/A221722/b221722.txt">Table of n, a(n) for n = 1..13</a>
%e Some solutions for n=3
%e ..0..0..0..1....0..0..0..2....0..1..2..1....0..3..1..1....0..0..0..1
%e ..0..1..1..2....0..4..1..1....0..4..0..0....0..1..0..1....0..4..2..2
%e ..0..2..5..0....0..3..0..1....0..1..1..2....0..2..0..3....2..0..0..1
%Y Cf. A221723.
%K nonn
%O 1,1
%A _R. H. Hardin_, Jan 22 2013