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A179117
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a(n) = Sum_{d|n} phi(d^phi(d)).
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1
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1, 2, 7, 10, 501, 20, 100843, 2058, 354301, 4502, 23579476911, 6940, 21505924728445, 3327788, 1366875507, 2147485706, 45798768824157052689, 11691722, 98646963440126439346903, 10240004510, 4203330006607501
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OFFSET
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1,2
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COMMENTS
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phi(n) = A000010(n) is the Euler totient function of n.
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LINKS
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FORMULA
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Equals one-half the logarithmic derivative of A179116.
a(n) = Sum_{k=1..n} phi(gcd(n,k)^phi(gcd(n,k)))/phi(n/gcd(n,k)). - Richard L. Ollerton, May 09 2021
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PROG
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(PARI) {a(n)=sumdiv(n, d, eulerphi(d^eulerphi(d)))}
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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