A275159 Primes p such that p-1 is the value of totient function of a product of distinct Fermat numbers (A000215).

2, 3, 5, 17, 257, 65537, 548898078721, 1151122703583805441, 77370970260794891965562881, 632834090662785970268956262401, 1327149278901642923121482163604684801, 2787593149816327845958662202634335514787841, 91343852333181430856373443055921906148567941121

Offset: 1

Author

Jaroslav Krizek, Nov 13 2016

Keywords

• nonn

Comments

Primes p such that p-1 = phi(A001317(x)) has solution.

Examples

			Prime 548898078721 is in the sequence because 548898078720 = phi(1095216660735) = phi(3*5*17*4294967297); all numbers 3, 5, 17 and 4294967297 are terms of A000215 (Fermat numbers).
		

Crossrefs

Supersequence of A019434 (Fermat primes) and A092506 (primes of the form 2^n+1).

Cf. A000010, A000215, A001317, A019434, A092506.

Programs

Magma

Set(Sort([EulerPhi(k)+1: k in [A001317(n)] | IsPrime(EulerPhi(k)+1)]));

Extensions

a(13) from Jinyuan Wang, Nov 01 2020