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Search: id:A155152
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| A155152 |
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Numbers n such that 2*3^n-1 is prime |
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+0
2
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| 1, 2, 3, 6, 7, 8, 11, 13, 14, 15, 19, 20, 22, 23, 24, 26, 34, 37, 39, 40, 41, 42, 44, 46, 47, 48, 51, 53, 57, 62, 63, 64, 66, 68, 73, 74, 75, 79
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OFFSET
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1,2
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FORMULA
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a(n)=13*n^2+3*n+1 [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Jan 21 2009]
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EXAMPLE
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For n=1, 2*3-1=5; n=3, 2*3^3-1=53; n=12, 2*3^12-1=1062881
For n=1, a(1)=17; n=7, a(7)=659 [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Jan 21 2009]
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CROSSREFS
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Cf. A155153
Sequence in context: A064472 A001422 A097757 this_sequence A098740 A116046 A069579
Adjacent sequences: A155149 A155150 A155151 this_sequence A155153 A155154 A155155
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KEYWORD
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nonn
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AUTHOR
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Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Jan 21 2009
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EXTENSIONS
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Numbers n such that 13*n^2+3*n+1 is prime Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Jan 21 2009
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