cp's OEIS Frontend

A221826 Number of nX4 arrays of occupancy after each element moves to some horizontal, vertical or antidiagonal neighbor, without 2-loops or left turns.

%I A221826 #6 Jul 23 2025 02:16:23
%S A221826 0,73,2879,115417,4755445,194407111,7954432829,325446165881,
%T A221826 13315083231576,544765825231628,22288229643043523,911887582567144091,
%U A221826 37308434607556030347,1526415443763878545790,62450867501566841285468
%N A221826 Number of nX4 arrays of occupancy after each element moves to some horizontal, vertical or antidiagonal neighbor, without 2-loops or left turns.
%C A221826 Column 4 of A221828
%H A221826 R. H. Hardin, <a href="/A221826/b221826.txt">Table of n, a(n) for n = 1..46</a>
%e A221826 Some solutions for n=3
%e A221826 ..0..2..2..1....1..1..1..1....0..2..2..2....0..2..0..2....0..1..0..1
%e A221826 ..1..0..1..0....2..1..1..0....0..1..1..1....2..1..0..1....0..3..1..2
%e A221826 ..2..1..1..1....0..2..2..0....1..0..1..1....1..1..2..0....1..1..2..0
%K A221826 nonn
%O A221826 1,2
%A A221826 _R. H. Hardin_ Jan 26 2013