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A298479
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Matula-Goebel numbers of rooted trees in which all positive outdegrees are different.
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2
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1, 2, 4, 6, 7, 8, 12, 16, 19, 24, 28, 32, 38, 42, 48, 52, 53, 56, 57, 64, 68, 74, 84, 96, 104, 106, 107, 112, 128, 131, 134, 136, 152, 159, 163, 168, 178, 192, 208, 212, 224, 228, 256, 262, 263, 272, 296, 304, 311, 318, 336, 356, 384, 393, 416, 446, 448, 456
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OFFSET
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1,2
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LINKS
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Table of n, a(n) for n=1..58.
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EXAMPLE
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Sequence of trees begins:
1 o
2 (o)
4 (oo)
6 (o(o))
7 ((oo))
8 (ooo)
12 (oo(o))
16 (oooo)
19 ((ooo))
24 (ooo(o))
28 (oo(oo))
32 (ooooo)
38 (o(ooo))
42 (o(o)(oo))
48 (oooo(o))
52 (oo(o(o)))
53 ((oooo))
56 (ooo(oo))
57 ((o)(ooo))
64 (oooooo)
68 (oo((oo)))
74 (o(oo(o)))
84 (oo(o)(oo))
96 (ooooo(o))
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MATHEMATICA
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MGtree[n_]:=If[n===1, {}, MGtree/@Flatten[Cases[FactorInteger[n], {p_, k_}:>Table[PrimePi[p], {k}]]]];
doQ[n_]:=Or[n===1, UnsameQ@@Length/@Cases[MGtree[n], {__}, {0, Infinity}]];
Select[Range[1000], doQ]
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CROSSREFS
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Cf. A000081, A001221, A004111, A007097, A032305, A061775, A111299, A276625, A290760, A297571, A298120, A298422, A298424, A298478.
Sequence in context: A352089 A358458 A014855 * A015924 A096750 A088458
Adjacent sequences: A298476 A298477 A298478 * A298480 A298481 A298482
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KEYWORD
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nonn
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AUTHOR
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Gus Wiseman, Jan 19 2018
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STATUS
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approved
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