Fermat number
nounEtymology Named after French lawyer and amateur mathematician Pierre de Fermat (1601–1665).
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Mathematics, Number theory, Sciences An integer which is one more than two raised to a power which is itself a power of two (i.e., is expressible in the form 2^(2ⁿ)+1 for some n>0); equivalently, a number that is one more than two raised to some power (is expressible as 2ⁿ+1) and is prime.