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Search: id:A093179
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| A093179 |
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Smallest factor of the n-th Fermat number F(n) = 2^(2^n)+1. |
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+0
4
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| 3, 5, 17, 257, 65537, 641, 274177, 59649589127497217, 1238926361552897, 2424833, 45592577, 319489, 114689, 2710954639361
(list; graph; listen)
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OFFSET
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0,1
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LINKS
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Ivars Peterson, Cracking Fermat Numbers.
Eric Weisstein's World of Mathematics, Fermat Number
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EXAMPLE
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F(0) = 2^(2^0)+ 1 = 3, prime.
F(5) = 2^(2^5)+ 1 = 4294967297 = 641*6700417.
So 3 as the 0-th entry and 641 is the 5-th term.
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PROGRAM
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(PARI) g(n)=for(x=9, n, y=Vec(ifactor(2^(2^x)+1)); print1(y[1]", ")) - Cino Hilliard (hillcino368(AT)hotmail.com), Jul 04 2007
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CROSSREFS
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Cf. A000051, A070592.
Leading entries in triangle A050922.
Sequence in context: A019434 A164307 A125045 this_sequence A067387 A050922 A070592
Adjacent sequences: A093176 A093177 A093178 this_sequence A093180 A093181 A093182
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KEYWORD
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nonn,more,hard
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AUTHOR
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Eric Weisstein (eric(AT)weisstein.com), Mar 27, 2004
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EXTENSIONS
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Edited by N. J. A. Sloane (njas(AT)research.att.com), Jul 02 2008 at the suggestion of R. J. Mathar
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