cp's OEIS Frontend

A221822 Number of nX3 arrays of occupancy after each element stays put or moves to some horizontal or vertical neighbor, without consecutive moves in the same direction.

%I A221822 #6 Jul 23 2025 02:16:01
%S A221822 6,252,6711,190756,5374720,151592441,4274867564,120554575328,
%T A221822 3399703708400,95873611077468,2703690754567558,76245627705373885,
%U A221822 2150170395738132532,60636036995518426808,1709970985328543058485
%N A221822 Number of nX3 arrays of occupancy after each element stays put or moves to some horizontal or vertical neighbor, without consecutive moves in the same direction.
%C A221822 Column 3 of A221824
%H A221822 R. H. Hardin, <a href="/A221822/b221822.txt">Table of n, a(n) for n = 1..180</a>
%F A221822 Empirical: a(n) = 18*a(n-1) +312*a(n-2) -187*a(n-3) -13565*a(n-4) -20614*a(n-5) +158772*a(n-6) +381840*a(n-7) -1501245*a(n-8) -3110200*a(n-9) +13397334*a(n-10) -5218282*a(n-11) -30257641*a(n-12) +22527453*a(n-13) +59810156*a(n-14) -71002519*a(n-15) -62823023*a(n-16) +51211271*a(n-17) +211220974*a(n-18) -214821233*a(n-19) -158156578*a(n-20) +147778970*a(n-21) +223640148*a(n-22) -182698582*a(n-23) +171412*a(n-24) -59513311*a(n-25) +67158528*a(n-26) -136639431*a(n-27) +148395775*a(n-28) -84660389*a(n-29) +39605263*a(n-30) -6661260*a(n-31) +3867558*a(n-32) -132564*a(n-33) +150444*a(n-34) -5832*a(n-35)
%e A221822 Some solutions for n=3
%e A221822 ..1..3..1....0..1..0....0..2..1....1..1..1....1..0..0....2..0..1....1..1..1
%e A221822 ..0..1..0....1..3..0....2..0..0....0..4..1....4..0..3....3..0..1....1..1..2
%e A221822 ..0..2..1....0..3..1....1..2..1....1..0..0....0..0..1....0..2..0....0..0..2
%K A221822 nonn
%O A221822 1,1
%A A221822 _R. H. Hardin_ Jan 26 2013