Definition:Fermat Number/Sequence

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Sequence of Fermat Numbers

The sequence of Fermat numbers begins:

\(\ds 2^{\paren {2^0} } + 1\) \(=\) \(\ds 3\)
\(\ds 2^{\paren {2^1} } + 1\) \(=\) \(\ds 5\)
\(\ds 2^{\paren {2^2} } + 1\) \(=\) \(\ds 17\)
\(\ds 2^{\paren {2^3} } + 1\) \(=\) \(\ds 257\)
\(\ds 2^{\paren {2^4} } + 1\) \(=\) \(\ds 65 \, 537\)
\(\ds 2^{\paren {2^5} } + 1\) \(=\) \(\ds 4 \, 294 \, 967 \, 297\)
\(\ds 2^{\paren {2^6} } + 1\) \(=\) \(\ds 18 \, 446 \, 744 \, 073 \, 709 \, 551 \, 617\)

This sequence is A000215 in the On-Line Encyclopedia of Integer Sequences (N. J. A. Sloane (Ed.), 2008).


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