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A070639
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a(n) = (1/phi(n))*Sum_{k=1..n} phi(n*k).
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1
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1, 3, 5, 9, 11, 20, 19, 31, 33, 48, 43, 73, 59, 90, 88, 111, 97, 159, 121, 182, 165, 208, 173, 277, 211, 290, 263, 338, 271, 445, 309, 435, 396, 490, 414, 608, 433, 610, 544, 695, 531, 844, 585, 818, 745, 880, 697, 1080, 773, 1085, 918, 1126, 883, 1364, 995
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OFFSET
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1,2
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COMMENTS
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a(2n)>a(2n+1) for n>=5.
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LINKS
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MAPLE
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f:= n -> add(numtheory:-phi(n*k), k=1..n)/numtheory:-phi(n);
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MATHEMATICA
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Table[1/EulerPhi[n]*Sum[EulerPhi[n*k], {k, n}], {n, 60}] (* Harvey P. Dale, Dec 21 2015 *)
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PROG
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(PARI) for(n=1, 100, print1(sum(i=1, n, eulerphi(n*i))/eulerphi(n), ", "))
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CROSSREFS
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KEYWORD
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AUTHOR
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STATUS
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approved
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