A320061 Numbers k such that A215240(k) is prime.

1, 2, 144, 264, 540, 720, 888, 928, 1012, 1368, 1452, 1476, 1656, 1764, 1800, 1836, 1960, 2024, 2392, 2664, 2712, 2968, 3444, 3680, 3720, 3808, 4248, 4284, 4352, 4368, 4776, 5060, 5412, 5600, 6516, 6624, 6840, 6984, 7040, 7168, 7176, 7600, 7836, 7860, 8052, 8160, 8196, 8304, 8496, 8848, 9144

Offset

1,2

Links

Robert Israel, Table of n, a(n) for n = 1..10000

Max Alekseyev, PARI scripts for various problems (see invphi.gp there).

Example

a(3)=144 is in the sequence because phi(h)=144 for h = 185, 219, 273, 285, 292, 296, 304, 315, 364, 370, 380, 432, 438, 444, 456, 468, 504, 540, 546, 570, 630, and the sum of those is the prime 8311.

Maple

select(n -> isprime(convert(numtheory:-invphi(n), `+`)), [$1..10000]);

Prog

(PARI) isok(n) = isprime(vecsum(invphi(n))); \\ Michel Marcus, Oct 05 2018

Crossrefs

Cf. A215240, A320041.

Sequence in context: A283097 A371588 A304582 * A282296 A163275 A157073

Adjacent sequences: A320058 A320059 A320060 * A320062 A320063 A320064

Keyword

nonn

Author

Robert Israel, Oct 04 2018

Status

approved