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A298424 Matula-Goebel numbers of rooted trees in which all positive outdegrees are the same. 7
1, 2, 3, 4, 5, 8, 11, 14, 16, 31, 32, 49, 64, 76, 86, 127, 128, 256, 301, 424, 454, 512, 709, 722, 886, 1024, 1532, 1589, 1849, 2048, 2096, 3101, 3986, 4096, 5381, 6418, 6859, 8192, 9761, 9952, 11236, 13766, 13951, 14554, 16384, 19049, 21884, 22463, 23512 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..49.

EXAMPLE

Sequence of trees begins:

1   o

2   (o)

3   ((o))

4   (oo)

5   (((o)))

8   (ooo)

11  ((((o))))

14  (o(oo))

16  (oooo)

31  (((((o)))))

32  (ooooo)

49  ((oo)(oo))

64  (oooooo)

76  (oo(ooo))

86  (o(o(oo)))

127 ((((((o))))))

128 (ooooooo)

256 (oooooooo)

301 ((oo)(o(oo)))

424 (ooo(oooo))

454 (o((oo)(oo)))

512 (ooooooooo)

709 (((((((o)))))))

722 (o(ooo)(ooo))

886 (o(o(o(oo))))

MATHEMATICA

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

soQ[n_]:=Or[n===1, SameQ@@Length/@Cases[MGtree[n], {__}, {0, Infinity}]];

Select[Range[1000], soQ]

CROSSREFS

Cf. A000081, A000598, A001190, A003238, A007097, A111299, A214577, A276625, A298422, A298423, A298426.

Sequence in context: A281493 A181341 A174181 * A008812 A144679 A207890

Adjacent sequences:  A298421 A298422 A298423 * A298425 A298426 A298427

KEYWORD

nonn

AUTHOR

Gus Wiseman, Jan 19 2018

STATUS

approved

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Last modified February 22 09:43 EST 2019. Contains 320390 sequences. (Running on oeis4.)