87525

Appears in sequences

• Triangle read by rows: T(n,k) is the number of cycle-up-down permutations of {1,2,...,n} having k fixed points (0 <= k <= n). A permutation is said to be cycle-up-down if it is a product of up-down cycles. A cycle (b(1), b(2), ...) is said to be up-down if, when written with its smallest element in the first position, it satisfies b(1) < b(2) > b(3) < ... .at n=57A186363
• a(n) = number of subsets S of {1,2,...,n} having more than 1 element such that (difference between least two elements of S) = difference between greatest two elements of S.at n=18A357282