OFFSET
0,5
LINKS
Andrew Howroyd, Table of n, a(n) for n = 0..50
FORMULA
EXAMPLE
Non-isomorphic representatives of the a(4) = 5 loop-graphs:
{{1,1},{2,2},{3,3},{1,2}}
{{1,1},{2,2},{1,2},{1,3}}
{{1,1},{2,2},{1,2},{3,4}}
{{1,1},{2,2},{1,3},{2,3}}
{{1,1},{1,2},{1,3},{2,3}}
MATHEMATICA
Table[Length[Union[sysnorm /@ Select[Subsets[Subsets[Range[n], {1, 2}], {n}], Select[Tuples[#], UnsameQ@@#&]=={}&]]], {n, 0, 5}]
CROSSREFS
Without the choice condition we have A368598.
KEYWORD
nonn
AUTHOR
Gus Wiseman, Jan 13 2024
EXTENSIONS
a(8) onwards from Andrew Howroyd, Jan 14 2024
STATUS
approved