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A221605
Number of n X 4 arrays of occupancy after each element moves to some horizontal or antidiagonal neighbor, without move-in move-out left turns.
0
4, 53, 811, 12270, 184193, 2764070, 41480899, 622510123, 9342086217, 140197824897, 2103965848896, 31574471975014, 473841949757344, 7111003899609738, 106715702327136893, 1601495553082204043
OFFSET
1,1
COMMENTS
Column 4 of A221609.
EXAMPLE
Some solutions for n=3
..1..2..1..0....0..2..2..1....1..1..0..2....0..2..2..1....0..3..2..0
..1..2..0..1....1..2..1..0....0..2..3..0....1..0..0..0....0..0..2..1
..1..1..2..0....1..1..1..0....1..0..1..1....1..3..2..0....0..2..2..0
CROSSREFS
Cf. A221609.
Sequence in context: A241872 A109801 A099340 * A307172 A275801 A158259
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 20 2013
STATUS
approved