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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 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 May 6 03:25 EDT 2021. Contains 343580 sequences. (Running on oeis4.)