cp's OEIS Frontend

A221830 Number of 3Xn arrays of occupancy after each element moves to some horizontal, vertical or antidiagonal neighbor, without 2-loops or left turns.

%I A221830 #6 Jul 23 2025 02:16:44
%S A221830 0,14,202,2879,40983,583419,8304016,118195328,1682332699,23945477164,
%T A221830 340827864824,4851172222091,69049142818994,982810732310121,
%U A221830 13988833113623959,199110007092542464,2834031588079597413
%N A221830 Number of 3Xn arrays of occupancy after each element moves to some horizontal, vertical or antidiagonal neighbor, without 2-loops or left turns.
%C A221830 Row 3 of A221828
%H A221830 R. H. Hardin, <a href="/A221830/b221830.txt">Table of n, a(n) for n = 1..184</a>
%F A221830 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) for n>18
%e A221830 Some solutions for n=3
%e A221830 ..0..2..0....1..1..1....1..1..2....1..1..0....1..1..0....0..2..0....1..1..0
%e A221830 ..1..1..1....0..1..1....1..1..1....3..0..1....2..1..0....2..1..2....3..2..0
%e A221830 ..1..2..1....1..3..0....1..1..0....1..1..1....2..2..0....0..1..1....1..1..0
%K A221830 nonn
%O A221830 1,2
%A A221830 _R. H. Hardin_ Jan 26 2013