A015787 Numbers n such that phi(n) + 8 | sigma(n + 8), where phi = A000010 and sigma = A000203.

2, 18, 22, 34, 46, 48, 58, 94, 106, 132, 150, 166, 178, 180, 187, 214, 274, 346, 358, 394, 448, 466, 488, 526, 550, 562, 616, 624, 634, 660, 664, 744, 756, 772, 778, 782, 790, 798, 884, 886, 898, 934, 1138, 1174, 1186, 1354, 1366, 1438, 1618

Offset: 1

Author

Robert G. Wilson v

Keywords

• nonn

Comments

From Robert Israel, Jul 23 2020: (Start)

The first odd terms are 187, 2407, 98587, 388315.

If p > 5 is in A228353 then 2*p is in the sequence. (End)

Links

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

Crossrefs

Cf. A000010, A000203, A228353.

Programs

Maple

select(t -> numtheory:-sigma(t+8) mod (numtheory:-phi(t)+8)=0, [$1..2000]); # Robert Israel, Jul 23 2020

PARI

is(n)=!(sigma(n+8)%(eulerphi(n)+8)) \\ Charles R Greathouse IV, Sep 25 2012

Extensions

Corrected by Charles R Greathouse IV, Sep 25 2012