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A056778 Number of 3-element antichains on an unlabeled n-element set; equivalence classes of monotone Boolean functions of n variables with 3 mincuts under action of symmetric group S_n. 0
0, 0, 0, 2, 9, 30, 84, 202 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,4

REFERENCES

V. Jovovic and G. Kilibarda, On the number of Boolean functions in the Post classes F^{mu}_8, Diskretnaya Matematika, 11 (1999), no. 4, 127-138 (translated in Discrete Mathematics and Applications, 9, (1999), no. 6)

V. Jovovic, G. Kilibarda, On enumeration of the class of all monotone Boolean functions, in preparation.

LINKS

Table of n, a(n) for n=0..7.

Index entries for sequences related to Boolean functions

EXAMPLE

There are 30 3-element antichains on an unlabeled 5-element set: {{5},{4},{3}}, {{5},{4},{2,3}}, {{5},{4},{1,2,3}}, {{5},{3,4},{2,4}}, {{5},{3,4},{1,2}}, {{5},{3,4},{1,2,4}}, {{5},{2,3,4},{1,3,4}}, {{4,5},{3,5},{3,4}}, {{4,5},{3,5},{2,5}}, {{4,5},{3,5},{2,4}},{{4,5},{3,5},{2,3,4}}, {{4,5},{3,5},{1,2}}, {{4,5},{3,5},{1,2,5}}, {{4,5},{3,5},{1,2,4}}, {{4,5},{3,5},{1,2,3,4}}, {{4,5},{2,3},{1,3,5}}, {{4,5},{2,3,5},{2,3,4}}, {{4,5},{2,3,5},{1,3,5}}, {{4,5},{2,3,5},{1,3,4}}, {{4,5},{2,3,5},{1,2,3}}, {{4,5},{2,3,5},{1,2,3,4}}, {{4,5},{1,2,3,5},{1,2,3,4}}, {{3,4,5},{2,4,5},{2,3,5}}, {{3,4,5},{2,4,5},{1,4,5}}, {{3,4,5},{2,4,5},{1,3,5}}, {{3,4,5},{2,4,5},{1,2,3}}, {{3,4,5},{2,4,5},{1,2,3,5}}, {{3,4,5},{1,2,5},{1,2,3,4}}, {{3,4,5},{1,2,4,5},{1,2,3,5}}, {{2,3,4,5},{1,3,4,5},{1,2,4,5}}.

CROSSREFS

Cf. A056005, A047707, A055484, A055485.

Sequence in context: A182975 A228932 A196421 * A177111 A290746 A268586

Adjacent sequences:  A056775 A056776 A056777 * A056779 A056780 A056781

KEYWORD

more,nonn

AUTHOR

Vladeta Jovovic, Goran Kilibarda, Aug 17 2000

STATUS

approved

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Last modified February 28 23:19 EST 2020. Contains 332353 sequences. (Running on oeis4.)