|
%I #19 Sep 08 2022 08:46:15
%S 3,5,7,11,17,23,37,41,47,101,137,233,257,857,1297,1601,2017,4337,
%T 14401,16097,30497,62801,65537,77617,686737,18800897,255080417,
%U 12885295097,12918324737,96052225601,516392008697,7026644072737
%N Primes p such that phi(p) = phi(p-2) + phi(p-1); Phibonacci primes.
%C Primes from A065557; complement of A065572 with respect to A065557.
%C The first 5 known Fermat primes from A019434 are in sequence.
%e 17 is in this sequence because phi(17) = phi(15) + phi(16); 16 = 8 + 8.
%p select(t -> isprime(t) and t-1 = numtheory:-phi(t-1) + numtheory:-phi(t-2), [seq(i,i=3..10^6,2)]); # _Robert Israel_, Dec 22 2015
%o (Magma) [n: n in [3..5*10^7] | IsPrime(n) and EulerPhi(n) eq EulerPhi(n-2)+ EulerPhi(n-1)]
%Y Cf. A000010, A065557, A065572.
%K nonn
%O 1,1
%A _Jaroslav Krizek_, Dec 22 2015
|
