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A229340
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Euler totient function of the arithmetic derivative of n: a(n) = phi(n'), a(1) = 0.
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4
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0, 1, 1, 2, 1, 4, 1, 4, 2, 6, 1, 8, 1, 6, 4, 16, 1, 12, 1, 8, 4, 12, 1, 20, 4, 8, 18, 16, 1, 30, 1, 32, 6, 18, 4, 16, 1, 12, 8, 32, 1, 40, 1, 16, 24, 20, 1, 48, 6, 24, 8, 24, 1, 54, 8, 44, 10, 30, 1, 44, 1, 20, 32, 64, 6, 60, 1, 24, 12, 58, 1, 48, 1, 24, 40, 32, 6, 70, 1, 80, 36, 42, 1, 60, 10, 24, 16, 48, 1, 80, 8, 32, 16, 42, 8
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OFFSET
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1,4
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COMMENTS
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LINKS
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FORMULA
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EXAMPLE
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For n=4 phi(n')=phi(4')=phi(4)=2.
For n=7 phi(n')=phi(7')=phi(1)=1.
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MATHEMATICA
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PROG
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(PARI) rd(n) = {local(fac); if(n<1, 0, fac=factor(n); sum(i=1, matsize(fac)[1], n*fac[i, 2]/fac[i, 1]; )); }
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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Description/formula clarified and more terms added by Antti Karttunen, Oct 30 2017
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STATUS
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approved
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