A318128 Number of set-systems (finite sets of finite nonempty sets) with union {1,2,...,n} and intersection {}.

1, 0, 2, 84, 31478, 2147000136, 9223371998203475474, 170141183460469231537996491257596836636, 57896044618658097711785492504343953922551603929769020459976077632195066756398

Offset: 0

Author

Gus Wiseman, Aug 18 2018

Keywords

• nonn

Examples

			The a(2) = 2 set-systems are {{1},{2}}, and {{1},{2},{1,2}}.
		

Crossrefs

Cf. A000371, A001146, A003465, A119563, A131288.

Cf. A318128, A318129, A318130, A318131, A318132.

Programs

Mathematica

Table[Length[Select[Subsets[Rest[Subsets[Range[n]]]],And[Union@@#===Range[n],Intersection@@#=={}]&]],{n,4}]

Formula

Inverse binomial transform of A318129.