511584

Appears in sequences

• Triangle read by rows: T(n,k) is the number of binary trees (i.e., a rooted tree where each vertex has either 0, 1, or 2 children; and, when only one child is present, it is either a right child or a left child) with n edges and k pairs of adjacent vertices of outdegree 2.at n=40A126219
• Numbers k such that k' = concat(s,t) and k = s*t, where k' is the arithmetic derivative of k.at n=20A272780