Number of unordered collections of distinct nonempty subsets of an n-element set where each element appears in at most 2 subsets.
A178165
Number of unordered collections of distinct nonempty subsets of an n-element set where each element appears in at most 2 subsets.
Terms
- a(0) =1a(1) =2a(2) =8a(3) =59a(4) =652a(5) =9736a(6) =186478a(7) =4421018a(8) =126317785a(9) =4260664251a(10) =166884941780
External references
- oeis: A178165