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Search: id:A125734
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| A125734 |
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Primes of the form 4*3^k+1. |
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+0
1
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| 5, 13, 37, 109, 2917, 19131877, 57395629, 16210220612075905069, 3187367866510497232065375864429355521950801431840733951694899540869109890815626195932616388528013, 254244997489062154119688681828370010268347235132197783249391539881181660045297550875174703528321187968562717038040968333
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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Venkataraman showed that, for every p of this form, 3p is a perfect totient number (Cf. A082897).
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REFERENCES
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Venkataraman, T. (1975). "Perfect totient number". The Mathematics Student 43: 178. MR0447089.
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FORMULA
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4*3^n+1 where n belongs to A005537.
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EXAMPLE
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E.g. 37=4*3^2+1 is a prime of this form. 973=4*3^5+1=7*139 is not a prime, so is not included in this sequence.
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MATHEMATICA
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Do[p = 4*3^i + 1; If[PrimeQ@p, Print@p], {i, 0, 300}] (from Robert G. Wilson v (rgwv(at)rgwv.com), Feb 20 2007)
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CROSSREFS
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Sequence in context: A111057 A083413 A071100 this_sequence A129924 A080143 A077919
Adjacent sequences: A125731 A125732 A125733 this_sequence A125735 A125736 A125737
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KEYWORD
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nonn
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AUTHOR
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David Eppstein (eppstein(AT)ics.uci.edu), Feb 06 2007, Feb 07 2007
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EXTENSIONS
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2 more terms from Robert G. Wilson v, Feb 20 2007
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