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A304982 Number of unlabeled clutters (connected antichains) spanning up to n vertices with singleton edges allowed. 8
1, 2, 5, 19, 137 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

The initial terms 1, 2, 5, 19 are the same as A304981 but the remaining terms differ.

LINKS

Table of n, a(n) for n=0..4.

FORMULA

Partial sums of A304983.

EXAMPLE

Non-isomorphic representatives of the a(3) = 19 clutters:

{}

{{1}}

{{1,2}}

{{1,2,3}}

{{2},{1,2}}

{{1,3},{2,3}}

{{3},{1,2,3}}

{{1},{2},{1,2}}

{{1,2},{1,3},{2,3}}

{{3},{1,2},{2,3}}

{{3},{1,3},{2,3}}

{{2},{3},{1,2,3}}

{{1},{2},{3},{1,2,3}}

{{2},{3},{1,2},{1,3}}

{{3},{1,2},{1,3},{2,3}}

{{2},{3},{1,3},{2,3}}

{{1},{2},{3},{1,3},{2,3}}

{{2},{3},{1,2},{1,3},{2,3}}

{{1},{2},{3},{1,2},{1,3},{2,3}}

CROSSREFS

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

Sequence in context: A272906 A054926 A002786 * A039719 A198203 A014466

Adjacent sequences:  A304979 A304980 A304981 * A304983 A304984 A304985

KEYWORD

nonn

AUTHOR

Gus Wiseman, May 23 2018

STATUS

approved

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Last modified February 18 05:14 EST 2019. Contains 320245 sequences. (Running on oeis4.)