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A090872
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a(n) is the smallest number m greater than 1 such that m^(2^k)+1 for k=0,1,...,n are primes.
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10
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OFFSET
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0,1
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COMMENTS
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The first five terms of this sequence correspond to Fermat primes.
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LINKS
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Table of n, a(n) for n=0..7.
PrimeGrid, Generalized Fermat Progression Search
Carlos Rivera, Puzzle 137. Product of primes + 1, a square, The Prime Puzzles and Problems Connection.
Carlos Rivera (ed.), Prime Puzzle # 399, The Prime Puzzles and Problems Connection.
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EXAMPLE
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a(5)=7072833120 because 7072833120^2^k+1 for k=0,1,2,3,4,5 are primes.
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CROSSREFS
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Cf. A019434, A000215.
Cf. A090873-A090875.
All solutions for fixed n: A006093 (n=0), A070689 (n=1), A070325 (n=2), A070655 (n=3), A070694 (n=4), A235390 (n=5), A335805 (n=6), A337364 (n=7).
Sequence in context: A067089 A339027 A343121 * A283472 A225538 A212355
Adjacent sequences: A090869 A090870 A090871 * A090873 A090874 A090875
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KEYWORD
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nonn,more
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AUTHOR
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Farideh Firoozbakht, Jan 31 2004
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EXTENSIONS
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a(6) from Jens Kruse Andersen, May 06 2007
a(7) from Kellen Shenton, Aug 13 2020
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STATUS
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approved
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