cp's OEIS Frontend

A221825 Number of nX3 arrays of occupancy after each element moves to some horizontal, vertical or antidiagonal neighbor, without 2-loops or left turns.

%I A221825 #7 Jul 23 2025 02:16:15
%S A221825 0,16,202,2930,41618,592601,8434490,120053263,1708776751,24321871624,
%T A221825 346185271087,4927426856495,70134512879660,998259343308353,
%U A221825 14208720864088015,202239778618252032,2878579180120974241
%N A221825 Number of nX3 arrays of occupancy after each element moves to some horizontal, vertical or antidiagonal neighbor, without 2-loops or left turns.
%C A221825 Column 3 of A221828
%H A221825 R. H. Hardin, <a href="/A221825/b221825.txt">Table of n, a(n) for n = 1..210</a>
%F A221825 Empirical: a(n) = 17*a(n-1) -39*a(n-2) -14*a(n-3) +134*a(n-4) -161*a(n-5) +50*a(n-6) -147*a(n-7) +129*a(n-8) +215*a(n-9) -131*a(n-10) +53*a(n-11) -92*a(n-12) -97*a(n-13) +31*a(n-14) -27*a(n-15) +16*a(n-16) +6*a(n-17)
%e A221825 Some solutions for n=3
%e A221825 ..1..1..1....1..1..0....1..1..0....1..1..0....0..2..2....1..1..1....0..2..0
%e A221825 ..1..1..1....2..1..1....3..0..2....2..0..1....1..0..2....2..1..0....2..2..0
%e A221825 ..1..1..1....1..1..1....0..1..1....2..1..1....0..1..1....1..1..1....1..1..1
%K A221825 nonn
%O A221825 1,2
%A A221825 _R. H. Hardin_ Jan 26 2013