A048849 a(n) = prime(phi(n)) + phi(prime(n)).

3, 4, 7, 9, 17, 15, 29, 25, 35, 35, 59, 43, 77, 55, 65, 71, 111, 73, 127, 89, 109, 107, 161, 107, 167, 137, 163, 143, 215, 131, 239, 183, 207, 191, 237, 187, 307, 223, 255, 225, 351, 217, 371, 263, 285, 277, 409, 275, 407, 299, 363, 327, 479, 311, 429, 351, 419

Offset: 1

Author

N. J. A. Sloane

Keywords

• nonn
• easy

Comments

I made this up to demonstrate how easy it is to construct dull but unguessable sequences with short descriptions.

Links

• G. C. Greubel, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A000010, A000040, A048848.

Programs

Magma

[NthPrime(EulerPhi(n)) + EulerPhi(NthPrime(n)) : n in [1..100]]; // G. C. Greubel, Feb 22 2024

Maple

with(numtheory); [ seq(ithprime(phi(i))+phi(ithprime(i)),i=1..80) ];

Mathematica

Table[Prime[EulerPhi[n]] + EulerPhi[Prime[n]], {n,100}] (* G. C. Greubel, Feb 22 2024 *)

SageMath

[nth_prime(euler_phi(n)) + euler_phi(nth_prime(n)) for n in range(1,101)] # G. C. Greubel, Feb 22 2024

Extensions

Offset corrected by G. C. Greubel, Feb 22 2024