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Search: id:A156555
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| A156555 |
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Primes of the form 3^n-4 |
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+0
1
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| 5, 23, 239, 10460353199, 617673396283943, 450283905890997359, 36472996377170786399, 19383245667680019896796719, 67585198634817523235520443624317919
(list; graph; listen)
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OFFSET
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1,1
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FORMULA
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If 3^n-4 is prime then a[m]=3^n-4
a(k) = 3^A058959(k)-4. [From M. F. Hasler (MHasler(AT)univ-ag.fr), Oct 31 2009]
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EXAMPLE
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For n=2, a)2)=5; n=3, a(3)=23; n=5, a(5)=239;
a(1) = 3^2-4 = 5 is the smallest prime of that form. [From M. F. Hasler (MHasler(AT)univ-ag.fr), Oct 31 2009]
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PROGRAM
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(PARI) for( k=2, 999, is/*pseudo*/prime( p=3^k-4 ) & print1(p", ")) [From M. F. Hasler (MHasler(AT)univ-ag.fr), Oct 31 2009]
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CROSSREFS
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Cf. A058959
Sequence in context: A167576 A116151 A156187 this_sequence A116652 A072104 A086797
Adjacent sequences: A156552 A156553 A156554 this_sequence A156556 A156557 A156558
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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), Feb 10 2009
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EXTENSIONS
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Corrected a(5). M. F. Hasler (MHasler(AT)univ-ag.fr), Oct 31 2009
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