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A304817
Number of divisors of n that are either 1 or not a perfect power.
7
1, 2, 2, 2, 2, 4, 2, 2, 2, 4, 2, 5, 2, 4, 4, 2, 2, 5, 2, 5, 4, 4, 2, 6, 2, 4, 2, 5, 2, 8, 2, 2, 4, 4, 4, 6, 2, 4, 4, 6, 2, 8, 2, 5, 5, 4, 2, 7, 2, 5, 4, 5, 2, 6, 4, 6, 4, 4, 2, 11, 2, 4, 5, 2, 4, 8, 2, 5, 4, 8, 2, 8, 2, 4, 5, 5, 4, 8, 2, 7, 2, 4, 2, 11, 4, 4
OFFSET
1,2
COMMENTS
First differs from A183095 at a(80) = 8, A183095(80) = 7.
FORMULA
a(n) = A183096(n) + 1.
EXAMPLE
The a(72) = 8 divisors of 72 that are either 1 or not a perfect power are {1, 2, 3, 6, 12, 18, 24, 72}. Missing are {4, 8, 9, 36}.
MATHEMATICA
Table[DivisorSum[n, Boole[GCD@@FactorInteger[#][[All, 2]]==1]&], {n, 100}]
PROG
(PARI) a(n) = sumdiv(n, d, !ispower(d)); \\ Michel Marcus, May 19 2018
KEYWORD
nonn
AUTHOR
Gus Wiseman, May 18 2018
STATUS
approved