

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

Table of n, a(n) for n=1..59.


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

Cf. A000081, A000837, A007097, A289509, A302796, A316468, A316469, A316473, A316475, A316495.
Sequence in context: A254748 A217562 A088879 * A290822 A318186 A139363
Adjacent sequences: A316467 A316468 A316469 * A316471 A316472 A316473


KEYWORD

nonn


AUTHOR

Gus Wiseman, Jul 04 2018


STATUS

approved



