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Search: id:A075546
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| A075546 |
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Perfect powers n such that (n-9)/2 is prime. |
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+0
1
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| 343, 1331, 12167, 29791, 42875, 79507, 103823, 300763, 357911, 857375, 1520875, 2248091, 2924207, 6436343, 9393931
(list; graph; listen)
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OFFSET
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1,1
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EXAMPLE
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a(1)=7^3, a(2)=11^3, a(3)=23^3, a(4)=31^3, a(5)=35^3, a(6)=43^3, a(7)=47^3, a(8)=67^3, a(9)=71^3, a(10)=95^3, a(11)=115^3, a(12)=131^3, a(13)=143^3, a(14)=23^5 and a(15)=211^3; most are cubes.
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MATHEMATICA
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pp = Join[{1}, Select[ Range[10^7], Apply[GCD, Last[ Transpose[ FactorInteger[ # ]]]] > 1 & ]]; Select[pp, PrimeQ[(# - 9)/2] & ]
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CROSSREFS
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Sequence in context: A117689 A047739 A052084 this_sequence A167733 A167730 A016923
Adjacent sequences: A075543 A075544 A075545 this_sequence A075547 A075548 A075549
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KEYWORD
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easy,nonn
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AUTHOR
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Zak Seidov (zakseidov(AT)yahoo.com), Oct 11 2002
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EXTENSIONS
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Extended by Robert G. Wilson v (rgwv(AT)rgwv.com), Oct 14 2002
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