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

0, 16, 202, 2930, 41618, 592601, 8434490, 120053263, 1708776751, 24321871624, 346185271087, 4927426856495, 70134512879660, 998259343308353, 14208720864088015, 202239778618252032, 2878579180120974241

Offset: 1

Author

R. H. Hardin Jan 26 2013

Keywords

• nonn

Comments

Column 3 of A221828

Examples

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

Links

• R. H. Hardin, Table of n, a(n) for n = 1..210

Formula

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)