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Search: id:A063690
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| A063690 |
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Numbers n such that n-th prime - phi(n) - d(n) = (n+1)-th prime - phi(n+1) - d(n+1), where d(n) = number of divisors of n. |
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+0
1
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| 1, 12, 20, 44, 68, 74, 146, 284, 2204, 6884, 61454, 82934, 407924, 2792144, 3988424, 8380448
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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No more terms through 10^7. - Ryan Propper (rpropper(AT)stanford.edu), Aug 26 2005
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MATHEMATICA
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Do[If[Prime[n] - EulerPhi[n] - DivisorSigma[0, n] == Prime[n+1] - EulerPhi[n+1] - DivisorSigma[0, n+1], Print[n]], {n, 1, 10^7}] (Propper)
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PROGRAM
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(PARI) for(n=1, 40000, if(prime(n) - eulerphi(n) - numdiv(n)==prime(n+1) - eulerphi(n+1) - numdiv(n+1), print(n)))
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CROSSREFS
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Cf. A048783, A000040, A000010, A000005.
Adjacent sequences: A063687 A063688 A063689 this_sequence A063691 A063692 A063693
Sequence in context: A082800 A026041 A082296 this_sequence A109788 A025104 A060159
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KEYWORD
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nonn
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AUTHOR
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Jason Earls (zevi_35711(AT)yahoo.com), Aug 23 2001
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EXTENSIONS
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More terms from David Wasserman (wasserma(AT)spawar.navy.mil), Jul 18 2002
3 more terms from Ryan Propper (rpropper(AT)stanford.edu), Aug 26 2005
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