In this article, you state, “The first Fermat number is 22+1, or 5,” and later, “the first four Fermat numbers are prime, but [among] the rest, up to and now including the 24th, none are prime.” Almost all number theorists consider the first Fermat prime to be F0 = 220 + 1 = 3, so that the first five Fermat numbers are prime.

Solomon W. Golomb
University of Southern California
Los Angeles, Calif.

From the Nature Index

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