OFFSET
1,3
COMMENTS
The Matula-Goebel numbers of these trees are given by A324935.
EXAMPLE
The a(1) = 1 through a(6) = 17 trees:
o (o) (oo) (ooo) (oooo) (ooooo)
((o)) ((oo)) ((ooo)) ((oooo))
(o(o)) (o(oo)) (o(ooo))
(((o))) (oo(o)) (oo(oo))
(((oo))) (ooo(o))
((o(o))) (((ooo)))
(o((o))) ((o)(oo))
((((o)))) ((o(oo)))
((oo(o)))
(o((oo)))
(o(o(o)))
(oo((o)))
((((oo))))
(((o(o))))
((o((o))))
(o(((o))))
(((((o)))))
MATHEMATICA
durt[n_]:=Join@@Table[Select[Union[Sort/@Tuples[durt/@ptn]], UnsameQ@@Cases[#, {__}, {0, Infinity}]&], {ptn, IntegerPartitions[n-1]}];
Table[Length[durt[n]], {n, 10}]
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Gus Wiseman, Mar 21 2019
STATUS
approved