login
Number of labeled clutters (connected antichains) spanning some subset of {1,...,n}, if clutters of the form {{x}} are allowed for any vertex x.
8

%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