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, 0, 0, 2, 40, 1070, 38936, 1896220, 119912476, 9587033840
Offset: 0
Examples
In case of n = 3. | permutation --+------------------- 1 | [2, 3, 1, 2, 1, 3] 2 | [3, 1, 2, 1, 3, 2]
Extensions
a(9) from Alois P. Heinz, Nov 30 2018