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A019434 Fermat primes: primes of form 2^(2^n) + 1. +0
58
3, 5, 17, 257, 65537 (list; graph; listen)
OFFSET

1,1

REFERENCES

G. Everest, A. van der Poorten, I. Shparlinski and T. Ward, Recurrence Sequences, Amer. Math. Soc., 2003; see esp. p. 255.

R. K. Guy, Unsolved Problems in Number Theory, A3.

LINKS

C. Banderier, Pepin's Criterion For Fermat Numbers

C. K. Caldwell, The Prime Glossary, Fermat prime

Wilfrid Keller, Prime factors k.2^n + 1 of Fermat numbers F_m

Eric Weisstein's World of Mathematics, Link to a section of The World f Mathematics

Eric Weisstein's World of Mathematics, Fermat Number

Eric Weisstein's World of Mathematics, Fermat Prime

Wikipedia, Fermat prime

CROSSREFS

Cf. A000215.

Adjacent sequences: A019431 A019432 A019433 this_sequence A019435 A019436 A019437

Sequence in context: A023394 A056130 A078726 this_sequence A125045 A130728 A050922

KEYWORD

nonn,nice

AUTHOR

njas, David W. Wilson (davidwwilson(AT)comcast.net)

EXTENSIONS

It is conjectured that there are only 5 terms - certainly 2^(2^n) + 1 is composite for 5<=n<=21.

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Last modified May 16 01:24 EDT 2008. Contains 139630 sequences.


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