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A179115 a(n) = Sum_{d|n} phi(d^tau(d)). 1
1, 3, 7, 35, 21, 441, 43, 2083, 493, 4023, 111, 995801, 157, 16509, 27027, 526371, 273, 11338335, 343, 25604055, 111181, 106593, 507, 36692769241, 12521, 211071, 354787, 206540957, 813, 174960031461, 931, 537397283, 718857, 629139, 1029063 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

phi(n) = A000010(n) is the Euler totient function of n.

tau(n) = A000005(n) is the number of divisors of n.

LINKS

Table of n, a(n) for n=0..34.

FORMULA

Equals the logarithmic derivative of A179114.

a(n) = Sum_{k=1..n} phi(gcd(n,k)^tau(gcd(n,k)))/phi(n/gcd(n,k)). - Richard L. Ollerton, May 09 2021

PROG

(PARI) {a(n)=sumdiv(n, d, eulerphi(d^sigma(d, 0)))}

CROSSREFS

Cf. A179114, A000010 (phi), A000005 (tau).

Sequence in context: A192880 A318444 A334314 * A299300 A047907 A328420

Adjacent sequences:  A179112 A179113 A179114 * A179116 A179117 A179118

KEYWORD

nonn

AUTHOR

Paul D. Hanna, Jul 10 2010

STATUS

approved

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Last modified June 21 19:12 EDT 2021. Contains 345365 sequences. (Running on oeis4.)