A221783 Number of nX4 arrays of occupancy after each element moves to some horizontal or antidiagonal neighbor, without 2-loops or left turns

0, 3, 5, 16, 41, 105, 288, 735, 1981, 5156, 13685, 35973, 94940, 250271, 659721, 1739740, 4585933, 12092245, 31878636, 84050611, 221594145, 584232168, 1540316025

Offset

1,2

Comments

Column 4 of A221787

Links

Table of n, a(n) for n=1..23.

Formula

Empirical: a(n) = 5*a(n-2) + 5*a(n-3) + a(n-5). - Vaclav Kotesovec, May 23 2013

Example

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

Crossrefs

Sequence in context: A121646 A226205 A300533 * A243321 A099101 A208819

Adjacent sequences: A221780 A221781 A221782 * A221784 A221785 A221786

Keyword

nonn

Author

R. H. Hardin Jan 25 2013

Status

approved