A Carmichael number is a composite number that satisfies Fermat's congruence for every integer relatively prime to it.
The first few carmichael numbers are: 561, 1105, 1729, 2465, 2821, 6601, 8911, 10585, 15841, 29341, 41041, 46657, …
43 of the first one million positive integers are carmichael.
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