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 A304996 Number of unlabeled antichains of finite sets spanning up to n vertices with singleton edges allowed. 10
 1, 2, 6, 24, 166, 3266, 826308 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 LINKS Table of n, a(n) for n=0..6. EXAMPLE Non-isomorphic representatives of the a(3) = 24 antichains: {} {{1}} {{1,2}} {{1,2,3}} {{1},{2}} {{2},{1,2}} {{3},{1,2}} {{3},{1,2,3}} {{1,3},{2,3}} {{1},{2},{3}} {{1},{2},{1,2}} {{2},{3},{1,3}} {{2},{3},{1,2,3}} {{3},{1,2},{2,3}} {{3},{1,3},{2,3}} {{1,2},{1,3},{2,3}} {{1},{2},{3},{2,3}} {{1},{2},{3},{1,2,3}} {{2},{3},{1,2},{1,3}} {{2},{3},{1,3},{2,3}} {{3},{1,2},{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 Partial sums of A304997. Cf. A006126, A261005, A304997, A304998, A304999, A305000, A305001. Cf. A000372, A014466, A293993, A319639, A319721, A326704, A326972. Sequence in context: A012361 A308111 A121773 * A012711 A356579 A352059 Adjacent sequences: A304993 A304994 A304995 * A304997 A304998 A304999 KEYWORD nonn,more AUTHOR Gus Wiseman, May 23 2018 EXTENSIONS a(5)-a(6) from Andrew Howroyd, Aug 14 2019 STATUS approved

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Last modified July 15 06:58 EDT 2024. Contains 374324 sequences. (Running on oeis4.)