Number of permutations p of {1,...,n} such that exactly one element of {p(1),...,p(i-1)} is between p(i) and p(i+1) for all i from 2 to n-1.

A185030

Number of permutations p of {1,...,n} such that exactly one element of {p(1),...,p(i-1)} is between p(i) and p(i+1) for all i from 2 to n-1.