

A316470


MatulaGoebel numbers of unlabeled rooted RPMGtrees, meaning the MatulaGoebel numbers of the branches of any nonleaf node are relatively prime.


22



1, 2, 4, 6, 8, 12, 14, 16, 18, 24, 26, 28, 32, 36, 38, 42, 48, 52, 54, 56, 64, 72, 74, 76, 78, 84, 86, 96, 98, 104, 106, 108, 112, 114, 122, 126, 128, 144, 148, 152, 156, 162, 168, 172, 178, 182, 192, 196, 202, 208, 212, 214, 216, 222, 224, 228, 234, 244, 252
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OFFSET

1,2


COMMENTS

A prime index of n is a number m such that prime(m) divides n. A number is in the sequence iff it is 1 or its prime indices are relatively prime and already belong to the sequence.


LINKS



EXAMPLE

The sequence of all RPMGtrees preceded by their MatulaGoebel numbers begins:
1: o
2: (o)
4: (oo)
6: (o(o))
8: (ooo)
12: (oo(o))
14: (o(oo))
16: (oooo)
18: (o(o)(o))
24: (ooo(o))
26: (o(o(o)))
28: (oo(oo))
32: (ooooo)
36: (oo(o)(o))
38: (o(ooo))
42: (o(o)(oo))


MATHEMATICA

primeMS[n_]:=If[n===1, {}, Flatten[Cases[FactorInteger[n], {p_, k_}:>Table[PrimePi[p], {k}]]]];
Select[Range[1000], Or[#==1, And[GCD@@primeMS[#]==1, And@@#0/@primeMS[#]]]&]


CROSSREFS



KEYWORD

nonn


AUTHOR



STATUS

approved



