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A339871
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Number of primes p for which the p-adic valuation of phi(n) exceeds the p-adic valuation of n-1, with a(1) = 0 by convention.
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2
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0, 0, 0, 1, 0, 1, 0, 1, 1, 1, 0, 1, 0, 2, 1, 1, 0, 2, 0, 1, 1, 2, 0, 1, 1, 2, 1, 1, 0, 1, 0, 1, 1, 1, 2, 2, 0, 2, 2, 1, 0, 2, 0, 2, 2, 2, 0, 1, 1, 2, 1, 1, 0, 2, 2, 2, 1, 2, 0, 1, 0, 3, 2, 1, 1, 1, 0, 1, 1, 1, 0, 2, 0, 2, 2, 2, 2, 2, 0, 1, 1, 2, 0, 2, 1, 3, 2, 2, 0, 2, 1, 2, 2, 2, 2, 1, 0, 3, 3, 2, 0, 1, 0, 2, 2
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OFFSET
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1,14
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LINKS
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FORMULA
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PROG
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(PARI) A339871(n) = if(1==n, 0, my(s=0); for(k=1, n, my(p=prime(k)); if(valuation(eulerphi(n), p)>valuation(n-1, p), s++)); (s));
(PARI) A339871(n) = if(1==n, 0, my(f=factor(eulerphi(n))); sum(i=1, #f~, f[i, 2]>valuation(n-1, f[i, 1])));
(PARI) A339871(n) = omega(eulerphi(n)/gcd(n-1, eulerphi(n)));
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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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