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, 5, 36, 466, 8942, 240366, 8576860, 392952468, 22470271108

Offset

0,3

Links

Table of n, a(n) for n=0..9.

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

Cf. A176127, A322179.

Sequence in context: A194958 A241346 A132686 * A351019 A252782 A292194

Adjacent sequences: A322177 A322178 A322179 * A322181 A322182 A322183

Keyword

nonn,more

Author

Seiichi Manyama, Nov 30 2018

Extensions

a(9) from Alois P. Heinz, Nov 30 2018

Status

approved