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A298536 Matula-Goebel numbers of rooted trees such that every branch of the root has a different number of leaves. 5
1, 2, 3, 5, 7, 11, 13, 14, 17, 19, 21, 23, 26, 29, 31, 34, 35, 37, 38, 39, 41, 43, 46, 47, 51, 53, 57, 58, 59, 61, 65, 67, 69, 71, 73, 74, 77, 79, 82, 83, 85, 86, 87, 89, 94, 95, 97, 101, 103, 106, 107, 109, 111, 113, 115, 118, 122, 123, 127, 129, 131, 133 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
LINKS
EXAMPLE
Sequence of trees begins:
1 o
2 (o)
3 ((o))
5 (((o)))
7 ((oo))
11 ((((o))))
13 ((o(o)))
14 (o(oo))
17 (((oo)))
19 ((ooo))
21 ((o)(oo))
23 (((o)(o)))
26 (o(o(o)))
29 ((o((o))))
31 (((((o)))))
34 (o((oo)))
35 (((o))(oo))
37 ((oo(o)))
38 (o(ooo))
39 ((o)(o(o)))
41 (((o(o))))
43 ((o(oo)))
46 (o((o)(o)))
47 (((o)((o))))
MATHEMATICA
nn=2000;
primeMS[n_]:=If[n===1, {}, Flatten[Cases[FactorInteger[n], {p_, k_}:>Table[PrimePi[p], {k}]]]];
leafcount[n_]:=If[n===1, 1, With[{m=primeMS[n]}, If[Length[m]===1, leafcount[First[m]], Total[leafcount/@m]]]];
Select[Range[nn], UnsameQ@@leafcount/@primeMS[#]&]
CROSSREFS
Sequence in context: A097312 A095179 A074895 * A331784 A325162 A331635
KEYWORD
nonn
AUTHOR
Gus Wiseman, Jan 20 2018
STATUS
approved

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Last modified March 28 22:04 EDT 2024. Contains 371254 sequences. (Running on oeis4.)