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A037176
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Numbers n such that us(n) = number of primes <= n, where usigma(n) = sum of unitary divisors of n (A034448), us(n) is usigma(n)-n.
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0
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1, 2, 56, 80, 85, 2527, 2569, 2723, 2807, 7864, 7976, 22941, 113488, 174449, 461403, 1302379, 8513821, 14348051, 70110091, 70111621, 70112369, 249046528
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OFFSET
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1,2
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LINKS
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PROG
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(PARI) us(n) = sumdiv(n, d, if(gcd(d, n/d)==1, d)); f(n)=s=0; for(x=1, n, if(isprime(x), s++)); s; for(n=1, 10^6, if(us(n)-n==f(n), print(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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EXTENSIONS
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STATUS
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approved
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