This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A290689 Number of transitive rooted trees with n nodes. 72
 1, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 88, 143, 229, 370, 592, 955, 1527, 2457, 3929 (list; graph; refs; listen; history; text; internal format)
 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 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 Cf. A000081, A004111, A279861, A290822. Sequence in context: A206139 A023440 A225396 * A191869 A077373 A202278 Adjacent sequences:  A290686 A290687 A290688 * A290690 A290691 A290692 KEYWORD nonn,more AUTHOR Gus Wiseman, Oct 19 2017 EXTENSIONS a(20) from Robert Price, Sep 13 2018 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified July 21 06:55 EDT 2019. Contains 325192 sequences. (Running on oeis4.)