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Matula-Goebel numbers of rooted trees that are not identity trees but whose non-leaf terminal subtrees are all different.
5

%I #6 Mar 22 2019 00:33:56

%S 4,7,8,12,14,16,17,19,20,21,24,28,32,34,35,37,38,40,42,43,44,48,51,52,

%T 53,56,57,59,64,67,68,70,71,73,74,76,77,80,84,85,86,88,89,91,95,96,

%U 102,104,106,107,112,114,116,118,124,128,129,131,133,134,136,139

%N Matula-Goebel numbers of rooted trees that are not identity trees but whose non-leaf terminal subtrees are all different.

%C An unlabeled rooted tree is an identity tree if there are no repeated branches directly under the same root.

%H Gus Wiseman, <a href="/A324978/a324978.png">The first 36 trees together with their Matula-Goebel numbers</a>.

%F Complement of A276625 in A324935.

%e The sequence of trees together with the Matula-Goebel numbers begins:

%e 4: (oo)

%e 7: ((oo))

%e 8: (ooo)

%e 12: (oo(o))

%e 14: (o(oo))

%e 16: (oooo)

%e 17: (((oo)))

%e 19: ((ooo))

%e 20: (oo((o)))

%e 21: ((o)(oo))

%e 24: (ooo(o))

%e 28: (oo(oo))

%e 32: (ooooo)

%e 34: (o((oo)))

%e 35: (((o))(oo))

%e 37: ((oo(o)))

%e 38: (o(ooo))

%e 40: (ooo((o)))

%e 42: (o(o)(oo))

%e 43: ((o(oo)))

%t mgtree[n_]:=If[n==1,{},mgtree/@Flatten[Cases[FactorInteger[n],{p_,k_}:>Table[PrimePi[p],{k}]]]];

%t Select[Range[100],And[!And@@Cases[mgtree[#],q:{__}:>UnsameQ@@q,{0,Infinity}],UnsameQ@@Cases[mgtree[#],{__},{0,Infinity}]]&]

%Y Cf. A000081, A004111, A007097, A196050, A276625, A317713, A324850, A324923, A324935, A324936, A324968, A324969, A324970, A324971, A324979.

%K nonn

%O 1,1

%A _Gus Wiseman_, Mar 21 2019