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A006982
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Number of unlabeled distributive lattices with n elements.
(Formerly M0700)
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5
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1, 1, 1, 1, 2, 3, 5, 8, 15, 26, 47, 82, 151, 269, 494, 891, 1639, 2978, 5483, 10006, 18428, 33749, 62162, 114083, 210189, 386292, 711811, 1309475, 2413144, 4442221, 8186962, 15077454, 27789108, 51193086, 94357143, 173859936, 320462062, 590555664, 1088548290, 2006193418, 3697997558, 6815841849, 12563729268, 23157428823, 42686759863, 78682454720, 145038561665, 267348052028, 492815778109, 908414736485
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,5
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REFERENCES
| J. Heitzig and J. Reinhold, Counting finite lattices, Algebra Universalis, 48 (2002), 43-53.
J. Heitzig and J. Reinhold, The number of unlabeled orders on fourteen elements, Order 17 (2000) no. 4, 333-341.
P. D. Lincoln, personal communication.
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
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LINKS
| M. Erne, J. Heitzig and J. Reinhold, On the number of distributive lattices, Electronic Journal of Combinatorics, 9 (2002), #R24.
J. Heitzig and J. Reinhold, Counting finite lattices, preprint no. 298, Institut fuer Mathematik, Universitaet Hanover, Germany, 1999.
Institut f. Mathematik, Univ. Hanover, Erne/Heitzig/Reinhold papers
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CROSSREFS
| Cf. A006981, A006966.
Sequence in context: A151518 A082095 A177486 * A054539 A026702 A000047
Adjacent sequences: A006979 A006980 A006981 * A006983 A006984 A006985
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KEYWORD
| hard,nonn,nice
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com).
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EXTENSIONS
| More terms from Jobst Heitzig (heitzig(AT)math.uni-hannover.de), Feb 02 2001. These were computed by the same algorithm that was used to enumerate the posets on 14 elements.
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