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A095683
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Number of prime power divisors of n. If n = product p_i^r_i then d = product {p_i^s_i, 2 <= s_i <= r_i, s_i is prime} is a prime power divisor of n.
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4
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1, 0, 0, 1, 0, 0, 0, 2, 1, 0, 0, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 2, 0, 0, 0, 0, 3, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 3, 0, 0, 0, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0
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OFFSET
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1,8
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COMMENTS
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The number of coreful divisors of n that are terms of A056166 (a divisor of n is coreful if it has the same set of distinct prime factors as n, cf. A307958). - Amiram Eldar, Oct 31 2023
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LINKS
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FORMULA
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EXAMPLE
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n=16: prime power divisors of 16 are {2^2, 2^3}, so a(16) = 2.
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MATHEMATICA
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Array[Boole[# == 1] + Times @@ Map[PrimePi, FactorInteger[#][[All, -1]] ] &, 120] (* Michael De Vlieger, Jul 19 2017 *)
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PROG
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(PARI) A095683(n) = { my(f = factor(n), m = 1); for (k=1, #f~, m *= primepi(f[k, 2]); ); m; } \\ Antti Karttunen, Jul 19 2017
(Python)
from sympy import factorint, primepi, prod
def a(n): return 1 if n==1 else prod(primepi(e) for e in factorint(n).values())
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CROSSREFS
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KEYWORD
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nonn,easy,mult
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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