4421018

Appears in sequences

• Number of unordered collections of distinct nonempty subsets of an n-element set where each element appears in at most 2 subsets.at n=7A178165
• Array read by antidiagonals: A(n,k) is the number of sets of nonempty subsets of a k-element set where each element appears in at most n subsets.at n=47A330964