OFFSET
1,3
COMMENTS
Trails are directed and pass through each (undirected) edge at most once in either of the two directions.
FORMULA
a(n) = Sum_{k = 0..n(n-1)/2} A357886(n,k).
CROSSREFS
KEYWORD
nonn,more,walk
AUTHOR
Max Alekseyev, Oct 16 2022
EXTENSIONS
a(9) from Bert Dobbelaere, Oct 17 2022
STATUS
approved