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A048143 Number of labeled connected simplicial complexes with n nodes. 142
1, 1, 1, 5, 84, 6348, 7743728, 2414572893530, 56130437190053299918162 (list; graph; refs; listen; history; text; internal format)



Also number of connected antichains on a labeled n-set.


Table of n, a(n) for n=0..8.

Patrick De Causmaecker, Stefan De Wannemacker, On the number of antichains of sets in a finite universe, arXiv:1407.4288 [math.CO], 2014.

Greg Huber, Letters to N. J. A. Sloane, May 1983 [Annotated, corrected, scanned copy]

Gus Wiseman, Every Clutter Is a Tree of Blobs, The Mathematica Journal, Vol. 19, 2017.

Gus Wiseman, Sequences enumerating clutters, antichains, hypertrees, and hyperforests, organized by labeling, spanning, and allowance of singletons.


For n=3 we could have 2 edges (in 3 ways), 3 edges (1 way), or 3 edges and a triangle (1 way), so a(3)=5.

a(5) = 1+75+645+1655+2005+1345+485+115+20+2 = 6348.


Cf. A094033, A094034, A094035, A094036, A094037.

Cf. A000666, A006126, A030019, A054921, A120338, A275307, A285572.

Sequence in context: A156720 A288163 A268880 * A216420 A137083 A198586

Adjacent sequences:  A048140 A048141 A048142 * A048144 A048145 A048146




Greg Huber, May 12 1983


More terms from Vladeta Jovovic, Jun 17 2006

Entry revised by N. J. A. Sloane, Jul 27 2006



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Last modified December 15 00:30 EST 2019. Contains 329988 sequences. (Running on oeis4.)