A221783 - OEIS

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

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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 * A368409 A371868 A243321

Adjacent sequences: A221780 A221781 A221782 * A221784 A221785 A221786

KEYWORD

nonn

AUTHOR

R. H. Hardin Jan 25 2013

STATUS

approved