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A078439 Sum_{k=1..n} gcd(k,n)*mu(gcd(k,n))^2. 0
1, 3, 5, 4, 9, 15, 13, 8, 12, 27, 21, 20, 25, 39, 45, 16, 33, 36, 37, 36, 65, 63, 45, 40, 40, 75, 36, 52, 57, 135, 61, 32, 105, 99, 117, 48, 73, 111, 125, 72, 81, 195, 85, 84, 108, 135, 93, 80, 84, 120, 165, 100, 105, 108, 189, 104, 185, 171, 117, 180, 121, 183, 156, 64 (list; graph; refs; listen; history; internal format)
OFFSET

1,2

FORMULA

a(n) = Sum_{d|n} d*mu(d)^2*phi(n/d). Multiplicative with a(p) = 2*p-1 and a(p^e) = 2*(p-1)*p^(e-1), e>1.

CROSSREFS

Cf. A008683, A000010, A063659.

Sequence in context: A200700 A075380 A177983 * A007063 A127397 A201271

Adjacent sequences:  A078436 A078437 A078438 * A078440 A078441 A078442

KEYWORD

mult,nonn

AUTHOR

Vladeta Jovovic (vladeta(AT)eunet.rs), Dec 31 2002

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Last modified February 15 15:20 EST 2012. Contains 205823 sequences.