822041

Appears in sequences

• Number of permutations of n elements not containing the consecutive pattern 123.at n=10A049774
• Triangle read by rows: T(n,k) is the number of permutations of {1,2,...,n} having k doubledescents (0 <= k <= n-2). We say that i is a doubledescent (also called a double fall) of a permutation p if p(i) > p(i+1) > p(i+2).at n=38A162975
• Exponential Riordan array, defining orthogonal polynomials related to permutations without double falls.at n=55A182822