930138522

Appears in sequences

• Number of rooted planar trees with n non-root nodes: circularly cycling the subtrees at the root gives equivalent trees.at n=19A003239
• Number of n-element subsets of {1,2,...,2n-1} whose elements sum to a multiple of n.at n=18A145855
• Number of elements in the mutation class of a quiver of type D_n.at n=16A159557
• a(n) = ceiling(binomial(2*n-1,n-1)/n).at n=18A188669