A067260 -id:A067260 - cp's OEIS frontend

A067262 Numbers k such that sigma(k+1) = 4*phi(k).

2, 6, 14, 20, 30, 54, 104, 114, 132, 140, 234, 252, 279, 314, 434, 539, 620, 644, 798, 860, 1064, 1080, 1154, 1287, 1308, 1500, 1595, 1715, 1904, 2232, 2294, 2375, 2736, 2772, 2925, 3212, 3219, 3684, 3834, 4014, 4070, 4344, 4464, 4730, 4959, 5075, 5159

Offset: 1

Benoit Cloitre, Feb 21 2002

nonn

Amiram Eldar, Table of n, a(n) for n = 1..8225

Cf. A000010, A000203, A067260, A067261, A067263.

Select[Range[5000], DivisorSigma[1,#+1] == 4*EulerPhi[#] &] (* Amiram Eldar, Apr 24 2022 *)

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

Original entry on oeis.org

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

Benoit Cloitre, Feb 21 2002

nonn

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

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

More terms from Amiram Eldar, Apr 24 2022

cp's OEIS Frontend

A067262 Numbers k such that sigma(k+1) = 4*phi(k).

Views

Author

Keywords

Links

Crossrefs

Programs

Mathematica