|
%I #10 May 23 2018 23:13:21
%S 1,2,4,12,115,6834,7783198,2414627236078,56130437209370100252471
%N Number of labeled clutters (connected antichains) spanning some subset of {1,...,n}, if clutters of the form {{x}} are allowed for any vertex x.
%F a(n > 0) = A198085(n) + 1.
%F a(n) = A305005(n) + n.
%e The a(3) = 12 clutters:
%e {}
%e {{1}}
%e {{2}}
%e {{3}}
%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 0,2
%A _Gus Wiseman_, May 23 2018
|
