A214428 Carmichael numbers n such that A002322(n) = 2^k * p, where k is an integer and p is a prime.

561, 1105, 2465, 278545, 3224065, 11119105, 2479305985, 123155771490305

Offset

1,1

Comments

Wright (2012) proves that given the 5 known Fermat primes (A019434), these are the only numbers possible.

Links

Table of n, a(n) for n=1..8.

Eric Weisstein's World of Mathematics, Carmichael Function.

Thomas Wright, The impossibility of certain types of Carmichael numbers, INTEGERS 12 (2012), A31.

Crossrefs

Cf. A002997 (Carmichael numbers), A002322, A019434, A293291.

Sequence in context: A083733 A339869 A375875 * A262043 A264012 A175737

Adjacent sequences: A214425 A214426 A214427 * A214429 A214430 A214431

Keyword

nonn,hard

Author

T. D. Noe, Jul 19 2012

Status

approved