2136960

Appears in sequences

• a(n) = (n+1)!/2 + (n-1)(n-1)!.at n=8A000780
• Triangle T(n,k), n>=3, 3<=k<=n, read by rows. Number of ways to make n selections without replacement from a circular array of n unlabeled cells (ignoring rotations and reflection), such that the first selection of a cell adjacent to previously selected cells occurs on the k-th selection.at n=47A249796