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A322179
The number of permutations of {1,2,...,n,1,2,...,n} with the property that there are k or more numbers between the two k's in the set for k=1,...,n.
1
1, 0, 0, 2, 40, 1070, 38936, 1896220, 119912476, 9587033840
OFFSET
0,4
EXAMPLE
In case of n = 3.
| permutation
--+-------------------
1 | [2, 3, 1, 2, 1, 3]
2 | [3, 1, 2, 1, 3, 2]
CROSSREFS
Sequence in context: A264713 A012637 A127429 * A012834 A304448 A012241
KEYWORD
nonn,more
AUTHOR
Seiichi Manyama, Nov 30 2018
EXTENSIONS
a(9) from Alois P. Heinz, Nov 30 2018
STATUS
approved