The OEIS is supported by the many generous donors to the OEIS Foundation.



Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 59th year, we have over 358,000 sequences, and we’ve crossed 10,300 citations (which often say “discovered thanks to the OEIS”).

Other ways to Give
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A299116 The number of sparse union-closed sets. That is, the number of union-closed sets on n elements containing the empty set and the universe, such that in average each set (not counting the empty set) has at most n/2 elements. 0
0, 0, 0, 2, 27, 3133, 5777931 (list; graph; refs; listen; history; text; internal format)



If there is a counterexample to the union-closed set conjecture, it is a sparse union-closed set.


Table of n, a(n) for n=1..7.

G. Brinkmann and R. Deklerck, Generation of Union-Closed Sets and Moore Families, arXiv:1701.03751 [math.CO], 2017.

G. Brinkmann and R. Deklerck, Generation of Union-Closed Sets and Moore Families, Journal of Integer Sequences, Vol.21 (2018), Article 18.1.7.


Cf. A108798, A102894, A193674, A102896.

Sequence in context: A113094 A327128 A320669 * A076113 A182335 A056013

Adjacent sequences: A299113 A299114 A299115 * A299117 A299118 A299119




Gunnar Brinkmann, Feb 05 2018



Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified December 7 03:44 EST 2022. Contains 358649 sequences. (Running on oeis4.)