A067245 Numbers k such that phi(k) divides (sigma(k+2) + sigma(k-2)).

5, 6, 13, 15, 33, 68, 117, 156, 168, 222, 259, 265, 313, 522, 644, 665, 750, 986, 1065, 1153, 1178, 1328, 1351, 1377, 1447, 1750, 1812, 1824, 1976, 2392, 2482, 3672, 3885, 4185, 4460, 4528, 5450, 5812, 5824, 6610, 6804, 7256, 7306, 8496, 8930, 9310

Offset

1,1

Links

Amiram Eldar, Table of n, a(n) for n = 1..1000

Mathematica

Select[Range[3, 10^4], Divisible[Plus @@ DivisorSigma[1, # + {-2, 2}], EulerPhi[#]] &] (* Amiram Eldar, Jun 11 2022 *)

Crossrefs

Cf. A000010, A000203.

Sequence in context: A047436 A334320 A061437 * A059176 A219978 A326657

Adjacent sequences: A067242 A067243 A067244 * A067246 A067247 A067248

Keyword

nonn

Author

Benoit Cloitre, Feb 20 2002

Status

approved