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Search: id:A105181
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| A105181 |
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Numbers n such that 2^(2*(n+1)) + 2^n - 1 is prime. |
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+0
1
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| 1, 2, 3, 4, 5, 6, 8, 10, 14, 22, 38, 42, 71, 118, 128, 159, 179, 214, 484, 951, 1148, 1162, 1427, 1532, 1692, 1861, 2261, 3760, 4575, 6974, 7295, 8367, 8463, 8600, 14878, 16165
(list; graph; listen)
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OFFSET
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1,2
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EXAMPLE
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2^4+2^1+1=19 prime so a(1)=1
2^6+2^2+1=67 prime so a(2)=2
2^8+2^3+1=263 prime so a(3)=3
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MATHEMATICA
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a[n_]:=2^(2*(n+1))+2^n-1; lst={}; Do[If[PrimeQ[a[n]], AppendTo[lst, n]], {n, 0, 7!}]; lst [From Vladimir Orlovsky (4vladimir(AT)gmail.com), Jan 03 2009]
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CROSSREFS
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Sequence in context: A086736 A017846 A129976 this_sequence A096120 A050030 A046889
Adjacent sequences: A105178 A105179 A105180 this_sequence A105182 A105183 A105184
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KEYWORD
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more,nonn
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AUTHOR
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Pierre CAMI (pierrecami(AT)tele2.fr), Apr 11 2005
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EXTENSIONS
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More terms from Ryan Propper (rpropper(AT)cs.stanford.edu), Jan 31 2008
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