cp's OEIS Frontend

A221823 Number of n X 4 arrays of occupancy after each element stays put or moves to some horizontal or vertical neighbor, without consecutive moves in the same direction.

%I A221823 #6 Jun 19 2025 22:35:49
%S A221823 13,2113,190756,18636989,1804472268,174820457922,16936005698353,
%T A221823 1640717334488903,158947987755078035,15398437448141904936,
%U A221823 1491757378064714004413,144517269678468770214198
%N A221823 Number of n X 4 arrays of occupancy after each element stays put or moves to some horizontal or vertical neighbor, without consecutive moves in the same direction.
%C A221823 Column 4 of A221824.
%H A221823 R. H. Hardin, <a href="/A221823/b221823.txt">Table of n, a(n) for n = 1..25</a>
%e A221823 Some solutions for n=3
%e A221823 ..0..1..0..2....1..0..1..1....0..1..0..1....0..3..0..0....0..0..2..0
%e A221823 ..1..4..0..0....2..3..2..0....1..2..0..4....1..1..1..2....2..0..4..0
%e A221823 ..0..0..1..3....0..1..1..0....1..2..0..0....0..1..1..2....1..2..1..0
%Y A221823 Cf. A221824.
%K A221823 nonn
%O A221823 1,1
%A A221823 _R. H. Hardin_, Jan 26 2013