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A190827
Number of permutations of 3 copies of 1..n introduced in order 1..n with no element equal to another within a distance of 2
0
0, 0, 1, 109, 12721, 2001240, 418539642, 113320421342, 38733396860601, 16350175635962731
OFFSET
1,4
EXAMPLE
Some solutions for n=4
..1....1....1....1....1....1....1....1....1....1....1....1....1....1....1....1
..2....2....2....2....2....2....2....2....2....2....2....2....2....2....2....2
..3....3....3....3....3....3....3....3....3....3....3....3....3....3....3....3
..1....4....4....1....4....4....4....4....4....4....4....1....4....4....4....4
..4....2....1....4....2....1....2....2....2....1....2....4....2....2....1....2
..2....1....2....3....1....2....1....3....3....2....3....3....1....1....2....3
..3....3....4....2....3....4....4....1....4....3....1....2....4....3....4....4
..4....2....1....1....4....3....3....4....1....4....4....4....3....4....3....1
..1....4....3....4....1....1....2....3....3....2....2....1....1....1....1....2
..2....1....2....2....2....4....1....2....4....1....3....3....2....2....2....4
..4....3....4....3....4....3....4....4....2....3....1....4....3....3....4....3
..3....4....3....4....3....2....3....1....1....4....4....2....4....4....3....1
CROSSREFS
Sequence in context: A357231 A227949 A144930 * A125044 A352466 A096209
KEYWORD
nonn
AUTHOR
R. H. Hardin May 21 2011
STATUS
approved