

A302594


Numbers whose prime indices other than 1 are equal prime numbers.


0



1, 2, 3, 4, 5, 6, 8, 9, 10, 11, 12, 16, 17, 18, 20, 22, 24, 25, 27, 31, 32, 34, 36, 40, 41, 44, 48, 50, 54, 59, 62, 64, 67, 68, 72, 80, 81, 82, 83, 88, 96, 100, 108, 109, 118, 121, 124, 125, 127, 128, 134, 136, 144, 157, 160, 162, 164, 166, 176, 179, 191, 192
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OFFSET

1,2


COMMENTS

A prime index of n is a number m such that prime(m) divides n.


LINKS

Table of n, a(n) for n=1..62.


EXAMPLE

Entry A302242 describes a correspondence between positive integers and multiset multisystems. In this case it gives the following sequence of set systems.
01: {}
02: {{}}
03: {{1}}
04: {{},{}}
05: {{2}}
06: {{},{1}}
08: {{},{},{}}
09: {{1},{1}}
10: {{},{2}}
11: {{3}}
12: {{},{},{1}}
16: {{},{},{},{}}
17: {{4}}
18: {{},{1},{1}}
20: {{},{},{2}}
22: {{},{3}}
24: {{},{},{},{1}}


MATHEMATICA

primeMS[n_]:=If[n===1, {}, Flatten[Cases[FactorInteger[n], {p_, k_}:>Table[PrimePi[p], {k}]]]];
Select[Range[400], MatchQ[Union[DeleteCases[primeMS[#], 1]], {_?PrimeQ}{}]&]


CROSSREFS

Cf. A000961, A001222, A003963, A005117, A006450, A007716, A056239, A076610, A275024, A047968, A281113, A295924, A301760, A302242, A302243.
Sequence in context: A325663 A277620 A031143 * A055492 A005459 A039216
Adjacent sequences: A302591 A302592 A302593 * A302595 A302596 A302597


KEYWORD

nonn


AUTHOR

Gus Wiseman, Apr 10 2018


STATUS

approved



