A006982 Number of unlabeled distributive lattices on n nodes.

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

Offset: 0

Author

N. J. A. Sloane

Keywords

• hard
• nonn
• nice

References

• P. D. Lincoln, personal communication.
• N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Links

• Jukka Kohonen, Table of n, a(n) for n = 0..60
• R. Belohlavek and V. Vychodil, Residuated lattices of size <=12, Order 27 (2010) 147-161, Table 6; DOI:10.1007/s11083-010-9143-7; Extended version.
• Aaron Chan, Erik Darpö, Osamu Iyama, and René Marczinzik, Periodic trivial extension algebras and fractionally Calabi-Yau algebras, arXiv:2012.11927 [math.RT], 2020.
• M. Erné, J. Heitzig and J. Reinhold, On the number of distributive lattices, Electronic Journal of Combinatorics, 9 (2002), #R24.
• D. J. Greenhoe, MRA-Wavelet subspace architecture for logic, probability, and symbolic sequence processing, 2014.
• J. Heitzig and J. Reinhold, The number of unlabeled orders on fourteen elements, Order 17 (2000) no. 4, 333-341.
• J. Heitzig and J. Reinhold, Counting finite lattices, preprint no. 298, Institut für Mathematik, Universität Hanover, Germany, 1999.
• J. Heitzig and J. Reinhold, Counting finite lattices, Algebra Universalis, 48 (2002), 43-53.
• Institut f. Mathematik, Univ. Hanover, Erne/Heitzig/Reinhold papers
• P. Jipsen, Planar distributive lattices up to size 15 (illustration of a(1..15)), personal web page, March 2014.
• P. Jipsen and N. Lawless, Generating all finite modular lattices of a given size, 2013.
• Jukka Kohonen, Cartesian lattice counting by the vertical 2-sum, Order (2021); see also on arXiv, arXiv:2007.03232 [math.CO], 2020.

Crossrefs

Cf. A006981, A006966, A343161.

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.