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%I #15 Feb 23 2019 10:09:10
%S 1,2,8,72,1824,220608,498243968,309072306743552,
%T 14369391925598802012151296
%N Number of labeled antichains of finite sets spanning some subset of {1,...,n} with singleton edges allowed.
%C Only the non-singleton edges are required to form an antichain.
%H Gus Wiseman, <a href="/A048143/a048143_4.txt">Sequences enumerating clutters, antichains, hypertrees, and hyperforests, organized by labeling, spanning, and allowance of singletons</a>.
%F Binomial transform of A304999.
%e The a(2) = 8 antichains:
%e {}
%e {{1}}
%e {{2}}
%e {{1,2}}
%e {{1},{2}}
%e {{1},{1,2}}
%e {{2},{1,2}}
%e {{1},{2},{1,2}}
%Y Cf. A006126, A261005, A304996, A304997, A304998, A304999, A305000, A305001.
%Y Cf. A000372, A003182, A014466, A293606, A293993, A306505, A320449, A321679.
%K nonn,more
%O 0,2
%A _Gus Wiseman_, May 23 2018
%E a(5)-a(8) from _Gus Wiseman_, May 31 2018
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