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A304986 Number of labeled clutters (connected antichains) spanning some subset of {1,...,n}, if clutters of the form {{x}} are allowed for any vertex x. 7
1, 2, 4, 12, 115, 6834, 7783198, 2414627236078, 56130437209370100252471 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

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

FORMULA

a(n > 0) = A198085(n) + 1.

a(n) = A305005(n) + n.

EXAMPLE

The a(3) = 12 clutters:

  {}

  {{1}}

  {{2}}

  {{3}}

  {{1,2}}

  {{1,3}}

  {{2,3}}

  {{1,2,3}}

  {{1,2},{1,3}}

  {{1,2},{2,3}}

  {{1,3},{2,3}}

  {{1,2},{1,3},{2,3}}

CROSSREFS

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

Sequence in context: A001696 A276534 A326969 * A013333 A154882 A062000

Adjacent sequences:  A304983 A304984 A304985 * A304987 A304988 A304989

KEYWORD

nonn

AUTHOR

Gus Wiseman, May 23 2018

STATUS

approved

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Last modified October 17 16:42 EDT 2019. Contains 328120 sequences. (Running on oeis4.)