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%I #23 Jul 02 2024 08:19:35
%S 1,1,1,1,2,4,11,33,129,577,3113,19092,132318,1011665
%N Number of lattices on n unlabeled nodes, up to duality.
%C Number of nonisomorphic lattices on n nodes, when from each pair of dual lattices only one is counted.
%H Volker Gebhardt and Stephen Tawn, <a href="https://research-data.westernsydney.edu.au/published/ff5d9c10519311ecb15399911543e199/">Catalogue of unlabelled lattices on up to 16 elements</a>, Western Sydney University (2018).
%F a(n) = (A006966(n) + A373894(n)) / 2.
%e a(5)=4: These are the four lattices. The dual of the last one is not counted.
%e o o o o
%e | / \ /|\ |
%e o o | o o o o
%e | | o \|/ / \
%e o o | o o o
%e | \ / \ /
%e o o o
%e |
%e o
%K nonn,hard,more
%O 0,5
%A _Jukka Kohonen_, Jun 30 2024