A067263 Numbers k such that sigma(k+1) = 5*phi(k).

2184, 6930, 7020, 7644, 17640, 18564, 23660, 25200, 27404, 71280, 83720, 120834, 129150, 179010, 189630, 191100, 198015, 224664, 228780, 273504, 285480, 302280, 304290, 322335, 328320, 335664, 437580, 443079, 449904, 451044, 462644, 478400, 483735, 619190, 627759

Offset: 1

Author

Benoit Cloitre, Feb 21 2002

Keywords

• nonn

Crossrefs

Cf. A000010, A000203, A067260, A067261, A067262.

Programs

Mathematica

Select[Range[7*10^5], DivisorSigma[1,#+1] == 5*EulerPhi[#] &] (* Amiram Eldar, Apr 24 2022 *)

Extensions

More terms from Amiram Eldar, Apr 24 2022