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A327536
Number of divisors of n that are 1, prime, or whose prime indices are relatively prime.
3
1, 2, 2, 3, 2, 4, 2, 4, 2, 4, 2, 6, 2, 4, 4, 5, 2, 5, 2, 6, 3, 4, 2, 8, 2, 4, 2, 6, 2, 8, 2, 6, 4, 4, 4, 8, 2, 4, 3, 8, 2, 7, 2, 6, 5, 4, 2, 10, 2, 5, 4, 6, 2, 6, 4, 8, 3, 4, 2, 12, 2, 4, 3, 7, 3, 8, 2, 6, 4, 8, 2, 11, 2, 4, 5, 6, 4, 7, 2, 10, 2, 4, 2, 11, 4
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 that are 1, prime, or whose prime indices are relatively prime are A327534. The maximum divisor of n satisfying the same conditions is A327535(n).
EXAMPLE
The divisors of 63 that are 1, prime, or whose prime indices are relatively prime are {1, 3, 7}, so a(63) = 3.
MATHEMATICA
Table[Length[Select[Divisors[n], #==1||PrimeQ[#]||GCD@@PrimePi/@First/@FactorInteger[#]==1&]], {n, 100}]
CROSSREFS
See link for additional cross-references.
Sequence in context: A327391 A365207 A083903 * A341946 A339915 A306509
KEYWORD
nonn
AUTHOR
Gus Wiseman, Sep 17 2019
STATUS
approved