A266164 Primes p such that phi(p) = phi(p-2) + phi(p-1); Phibonacci primes.

3, 5, 7, 11, 17, 23, 37, 41, 47, 101, 137, 233, 257, 857, 1297, 1601, 2017, 4337, 14401, 16097, 30497, 62801, 65537, 77617, 686737, 18800897, 255080417, 12885295097, 12918324737, 96052225601, 516392008697, 7026644072737

Offset

1,1

Comments

Primes from A065557; complement of A065572 with respect to A065557.

The first 5 known Fermat primes from A019434 are in sequence.

Links

Table of n, a(n) for n=1..32.

Example

17 is in this sequence because phi(17) = phi(15) + phi(16); 16 = 8 + 8.

Maple

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

Prog

(Magma) [n: n in [3..5*10^7] | IsPrime(n) and EulerPhi(n) eq EulerPhi(n-2)+ EulerPhi(n-1)]

Crossrefs

Cf. A000010, A065557, A065572.

Sequence in context: A238137 A090919 A065557 * A152999 A024967 A135246

Adjacent sequences: A266161 A266162 A266163 * A266165 A266166 A266167

Keyword

nonn

Author

Jaroslav Krizek, Dec 22 2015

Status

approved