OFFSET
1,2
COMMENTS
A prime index of n is a number m such that prime(m) divides n. For example, the prime indices of 55 are {3,5} with prime indices {{2},{3}}. Since 55 is not divisible by 2 or 3, it belongs to the sequence.
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
EXAMPLE
The sequence of multisets of multisets whose MM-numbers (see A302242) belong to the sequence begins:
1: {}
2: {{}}
4: {{},{}}
5: {{2}}
8: {{},{},{}}
11: {{3}}
16: {{},{},{},{}}
17: {{4}}
22: {{},{3}}
23: {{2,2}}
25: {{2},{2}}
31: {{5}}
32: {{},{},{},{},{}}
34: {{},{4}}
41: {{6}}
44: {{},{},{3}}
47: {{2,3}}
55: {{2},{3}}
59: {{7}}
62: {{},{5}}
64: {{},{},{},{},{},{}}
MATHEMATICA
primeMS[n_]:=If[n==1, {}, Flatten[Cases[FactorInteger[n], {p_, k_}:>Table[PrimePi[p], {k}]]]];
Select[Range[100], And@@Table[!Divisible[#, i], {i, Union@@primeMS/@primeMS[#]}]&]
CROSSREFS
KEYWORD
nonn
AUTHOR
Gus Wiseman, Mar 21 2019
STATUS
approved