cp's OEIS Frontend

A221508 Number of 2Xn arrays of occupancy after each element moves to some horizontal, diagonal or antidiagonal neighbor, without consecutive moves in the same direction.

%I A221508 #6 Jul 23 2025 02:00:53
%S A221508 0,9,44,446,3334,27540,219070,1766136,14168766,113870162,914550470,
%T A221508 7346946970,59015933032,474072774244,3808166264624,30590638905810,
%U A221508 245731343642532,1973934759524284,15856413036814582,127372929035331130
%N A221508 Number of 2Xn arrays of occupancy after each element moves to some horizontal, diagonal or antidiagonal neighbor, without consecutive moves in the same direction.
%C A221508 Row 2 of A221507
%H A221508 R. H. Hardin, <a href="/A221508/b221508.txt">Table of n, a(n) for n = 1..29</a>
%e A221508 Some solutions for n=3
%e A221508 ..0..3..0....0..4..0....1..2..0....0..2..2....1..0..0....0..2..0....0..1..0
%e A221508 ..1..1..1....1..0..1....1..2..0....0..2..0....0..4..1....1..2..1....0..3..2
%K A221508 nonn
%O A221508 1,2
%A A221508 _R. H. Hardin_ Jan 18 2013