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

0, 73, 2879, 115417, 4755445, 194407111, 7954432829, 325446165881, 13315083231576, 544765825231628, 22288229643043523, 911887582567144091, 37308434607556030347, 1526415443763878545790, 62450867501566841285468

Offset: 1

Author

R. H. Hardin Jan 26 2013

Keywords

• nonn

Comments

Column 4 of A221828

Examples

			Some solutions for n=3
..0..2..2..1....1..1..1..1....0..2..2..2....0..2..0..2....0..1..0..1
..1..0..1..0....2..1..1..0....0..1..1..1....2..1..0..1....0..3..1..2
..2..1..1..1....0..2..2..0....1..0..1..1....1..1..2..0....1..1..2..0
		

Links

• R. H. Hardin, Table of n, a(n) for n = 1..46