OFFSET
1,4
COMMENTS
A rooted tree is transitive if every proper terminal subtree is also a branch of the root. First differs from A206139 at a(13) = 143.
LINKS
Robert P. P. McKone, The transitive rooted tree with n=1 to n=22 nodes.
EXAMPLE
The a(7) = 8 trees are: (o(oooo)), (oo(ooo)), (o(o)((o))), (o(o)(oo)), (ooo(oo)), (oo(o)(o)), (oooo(o)), (oooooo).
MATHEMATICA
nn=18;
rtall[n_]:=If[n===1, {{}}, Module[{cas}, Union[Sort/@Join@@(Tuples[rtall/@#]&/@IntegerPartitions[n-1])]]];
Table[Length[Select[rtall[n], Complement[Union@@#, #]==={}&]], {n, nn}]
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Gus Wiseman, Oct 19 2017
EXTENSIONS
a(20) from Robert Price, Sep 13 2018
a(21)-a(22) from Robert P. P. McKone, Dec 16 2023
STATUS
approved