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A163167
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a(n) = sum_{d | phi(n)} mu( phi(d) ) * phi(n)/d, where phi = A000010.
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2
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1, 1, 3, 3, 5, 3, 6, 5, 6, 5, 15, 5, 9, 6, 10, 10, 20, 6, 21, 10, 9, 15, 36, 10, 25, 9, 21, 9, 41, 10, 30, 20, 25, 20, 18, 9, 33, 21, 18, 20, 50, 9, 51, 25, 18, 36, 72, 20, 51, 25, 40, 18, 65, 21, 50, 18, 33, 41, 87, 20, 45, 30, 33, 40, 36, 25, 75, 40, 61, 18, 120, 18, 66, 33, 50, 33
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OFFSET
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1,3
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COMMENTS
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LINKS
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FORMULA
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MAPLE
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with(numtheory):
local div:
div:=convert(divisors(phi(n)), list):
add( mobius(phi(d))*phi(n)/d, d=div) ;
end proc:
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MATHEMATICA
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Table[Sum[MoebiusMu[EulerPhi[d]] EulerPhi[n]/d, {d, Divisors[EulerPhi[n]]}], {n, 100}] (* Indranil Ghosh, Jul 17 2017 *)
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PROG
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(PARI) A163167(n) = sumdiv(eulerphi(n), d, moebius(eulerphi(d))*eulerphi(n)/d); \\ Antti Karttunen, Jul 17 2017
(PARI)
A289627(n) = sumdiv(n, d, moebius(eulerphi(d))*n/d);
(Python)
from sympy import mobius, totient, divisors
def a(n):
tn = totient(n)
return sum(mobius(totient(d))*tn//d for d in divisors(tn))
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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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STATUS
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approved
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