Carmichael numbers are numbers of this type that satisfy Fermat's Little Theorem, and the difference between them and their totient is at least two.
Carmichael numbers are numbers of this type that satisfy Fermat's Little Theorem, and the difference between them and their totient is at least two. Arbitrarily long sequences of these numbers can be found by starting at n-factorial plus two up through n-factorial plus n, and there is no jump in the function pi of x at each of them. These numbers are crossed out in the (*) Sieve of Eratosthenes, because they are divisible by a lower, circled number. For ten points, identify these numbers which have a factor besides one and themselves, and are thus not prime.
Carmichael numbers are numbers of this type that satisfy Fermat's Little Theorem, and the difference between them and their totient is at least two.
{composite} numbers