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A265229
Number of nX2 arrays containing 2 copies of 0..n-1 with no equal vertical neighbors and new values introduced sequentially from 0.
1
1, 2, 7, 43, 372, 4027, 51871, 773186, 13083385, 247698481, 5186925696, 119023766737, 2969884019977, 80056947698498, 2318432654628847, 71785166633148187, 2366425763631216756, 82748313392542136011
OFFSET
1,2
COMMENTS
Column 2 of A265232.
LINKS
Dmitry Efimov, Hafnian of two-parameter matrices, arXiv:2101.09722 [math.CO], 2021.
EXAMPLE
Some solutions for n=4
..0..1....0..1....0..0....0..0....0..1....0..1....0..1....0..1....0..1....0..1
..2..0....2..3....1..2....1..1....2..3....2..3....2..0....2..2....2..3....2..3
..3..2....1..2....3..1....2..2....3..1....3..0....1..3....0..1....3..0....1..0
..1..3....3..0....2..3....3..3....0..2....1..2....3..2....3..3....2..1....3..2
CROSSREFS
Cf. A265232.
Sequence in context: A144059 A352293 A078676 * A286684 A086331 A121418
KEYWORD
nonn
AUTHOR
R. H. Hardin, Dec 06 2015
STATUS
approved