... According to Carmichael's conjecture there are no 1's in this sequence. An even nontotient may be one more than a prime number, but never one less, since all numbers below a prime number are, by definition, coprime to it. To put it algebraically, for p prime: φ(p) = p − 1. Also, a pronic number n(n − 1) is certainly not a nontotient if n is prime since φ(p2) = p(p − 1). If a natural number n is a totient, it can be shown that n · 2k is a totient for all natural number k. There are infinitely many even nontotient numbers: indeed, there are infinitely many distinct primes p (such as 78557 and 271129, see Sierpinski number) such that all numbers of the form 2ap are nontotient, and every odd number has an even multiple which is a nontotient. References L. Havelock, A Few Observations on Totient and Cototient Valence from PlanetMath Integer sequences