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A327534
Numbers that are 1, prime, or whose prime indices are relatively prime.
6
1, 2, 3, 4, 5, 6, 7, 8, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 22, 23, 24, 26, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 40, 41, 42, 43, 44, 45, 46, 47, 48, 50, 51, 52, 53, 54, 55, 56, 58, 59, 60, 61, 62, 64, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76
OFFSET
1,2
COMMENTS
A prime index of n is a number m such that prime(m) divides n. The multiset of prime indices of n is row n of A112798. Numbers whose prime indices are relatively prime are A289509.
FORMULA
Equals the union of {1}, A000040, and A289509.
EXAMPLE
91 = 7 * 13 has prime indices {4,6}, which have a common divisor of 2, so 91 is not in the sequence.
MATHEMATICA
Select[Range[100], #==1||PrimeQ[#]||GCD@@PrimePi/@First/@FactorInteger[#]==1&]
CROSSREFS
See link for additional cross-references.
Complement of A327407.
Sequence in context: A183221 A317492 A324721 * A305732 A265999 A316502
KEYWORD
nonn
AUTHOR
Gus Wiseman, Sep 17 2019
STATUS
approved