2648395

Appears in sequences

• One-half the number of permutations of length n without rising or falling successions.at n=9A001266
• Triangle read by rows: T(n,k) = one-half number of permutations of length n with exactly k rising or falling successions, for n >= 1, 0 <= k <= n-1. T(1,0) = 1 by convention.at n=55A086856