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Number of labeled clutters (connected antichains) spanning some subset of {1,...,n} without singleton edges.
1

%I #10 Jun 16 2018 13:42:13

%S 1,1,2,9,111,6829,7783192,2414627236071,56130437209370100252463

%N Number of labeled clutters (connected antichains) spanning some subset of {1,...,n} without singleton edges.

%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 A048143 if we assume A048143(1) = 0.

%F a(n) = A198085(n) - n + 1. - _Gus Wiseman_, Jun 11 2018

%e The a(3) = 9 clutters:

%e {}

%e {{1,2}}

%e {{1,3}}

%e {{2,3}}

%e {{1,2,3}}

%e {{1,2},{1,3}}

%e {{1,2},{2,3}}

%e {{1,3},{2,3}}

%e {{1,2},{1,3},{2,3}}

%Y Cf. A048143, A198085, A261006, A304912, A304981, A304982, A304983, A304984, A304985, A304986.

%K nonn

%O 0,3

%A _Gus Wiseman_, May 23 2018