2350950

Appears in sequences

• Matrix square of Stirling2 triangle A008277: 2-levels set partitions of [n] into k first-level subsets.at n=49A039810
• Triangle of generalized Stirling numbers of 2nd kind.at n=50A046817
• Number of partitions of a 2n-set into colored blocks, such that exactly n colors are used and the colors are introduced in increasing order.at n=5A321712