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Search: id:A104904
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| A104904 |
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Numbers n such that d(n)*pi(n)=n, where d(n) is the number of positive divisors of n. |
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+0
4
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OFFSET
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1,1
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COMMENT
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Next term is greater than 3*10^9.
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EXAMPLE
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189961452 is in the sequence because d(189961452)=18; pi(189961452)=10553414 & 18*10553414=189961452.
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MATHEMATICA
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Do[If[DivisorSigma[0, n]*PrimePi[n] == n, Print[n]], {n, 2000000000}]
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CROSSREFS
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Cf. A063903, A104905, A104906.
Sequence in context: A129059 A129058 A129057 this_sequence A086563 A023328 A134656
Adjacent sequences: A104901 A104902 A104903 this_sequence A104905 A104906 A104907
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KEYWORD
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hard,more,nonn
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AUTHOR
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Farideh Firoozbakht (f.firoozbakht(AT)math.ui.ac.ir), Apr 12 2005
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