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

1,1

Links

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

Mathematica

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

Crossrefs

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

Sequence in context: A032643 A067664 A130800 * A107369 A151731 A009779

Adjacent sequences: A067259 A067260 A067261 * A067263 A067264 A067265

Keyword

nonn

Author

Benoit Cloitre, Feb 21 2002

Status

approved