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A070306
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a(n) = 2*phi(n)/2^omega(n).
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3
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2, 1, 2, 2, 4, 1, 6, 4, 6, 2, 10, 2, 12, 3, 4, 8, 16, 3, 18, 4, 6, 5, 22, 4, 20, 6, 18, 6, 28, 2, 30, 16, 10, 8, 12, 6, 36, 9, 12, 8, 40, 3, 42, 10, 12, 11, 46, 8, 42, 10, 16, 12, 52, 9, 20, 12, 18, 14, 58, 4, 60, 15, 18, 32, 24, 5, 66, 16, 22, 6, 70, 12, 72, 18, 20, 18, 30, 6, 78, 16
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OFFSET
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1,1
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COMMENTS
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Always an integer.
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LINKS
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FORMULA
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Sum_{k=1..n} ~ c * n / sqrt(log(n)), where c = A271547/sqrt(Pi) (Finch and Sebah, 2006). - Amiram Eldar, Apr 29 2022
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MATHEMATICA
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a[n_] := EulerPhi[n]/2^(PrimeNu[n] - 1); Array[a, 100] (* Amiram Eldar, Apr 29 2022 *)
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PROG
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(PARI) for(n=1, 100, print1(2*eulerphi(n)/2^omega(n), ", "))
(Python)
from sympy import totient as phi, primenu as omega
def a(n): return 2*phi(n)//2**omega(n)
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CROSSREFS
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KEYWORD
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easy,nonn
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AUTHOR
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EXTENSIONS
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Offset changed to 1 and a(1) inserted by Amiram Eldar, Apr 29 2022
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STATUS
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approved
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