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Search: id:A037176
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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
1
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| 1, 2, 56, 80, 85, 2527, 2569, 2723, 2807, 7864, 7976, 22941
(list; graph; listen)
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OFFSET
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1,2
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PROGRAM
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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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Adjacent sequences: A037173 A037174 A037175 this_sequence A037177 A037178 A037179
Sequence in context: A109796 A024029 A134501 this_sequence A045819 A056046 A080313
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KEYWORD
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nonn
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AUTHOR
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Naohiro Nomoto (6284968128(AT)geocities.co.jp)
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EXTENSIONS
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One more term from Jason Earls (jcearls(AT)cableone.net), Sep 06 2001
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