OFFSET
0,5
COMMENTS
Number of nonisomorphic lattices on n nodes, when from each pair of dual lattices only one is counted.
LINKS
Volker Gebhardt and Stephen Tawn, Catalogue of unlabelled lattices on up to 16 elements, Western Sydney University (2018).
EXAMPLE
a(5)=4: These are the four lattices. The dual of the last one is not counted.
o o o o
| / \ /|\ |
o o | o o o o
| | o \|/ / \
o o | o o o
| \ / \ /
o o o
|
o
CROSSREFS
KEYWORD
nonn,hard,more
AUTHOR
Jukka Kohonen, Jun 30 2024
STATUS
approved