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A322180
The number of permutations of {1,2,...,n,1,2,...,n} with the property that there are k or fewer numbers between the two k's in the set for k=1,...,n.
1
1, 1, 5, 36, 466, 8942, 240366, 8576860, 392952468, 22470271108
OFFSET
0,3
EXAMPLE
In case of n = 2.
| permutation
--+-------------
1 | [1, 1, 2, 2]
2 | [1, 2, 1, 2]
3 | [2, 1, 1, 2]
4 | [2, 1, 2, 1]
5 | [2, 2, 1, 1]
CROSSREFS
Sequence in context: A194958 A241346 A132686 * A351019 A252782 A292194
KEYWORD
nonn,more
AUTHOR
Seiichi Manyama, Nov 30 2018
EXTENSIONS
a(9) from Alois P. Heinz, Nov 30 2018
STATUS
approved