A114070 sigma(n) + n is a cube.

13, 76, 280, 4258, 4719, 4887, 12207, 13106, 41823, 42804, 51671, 54261, 56283, 65512, 77671, 95139, 98219, 135724, 147440, 149176, 177911, 220546, 239599, 279145, 285347, 285957, 299432, 308503, 312137, 335106, 350739, 525429, 611123, 634600, 663377, 700064

Offset: 1

Author

Giovanni Resta, Feb 13 2006

Keywords

• nonn

Examples

			sigma(13) + 13 = 27 = 3^3.
		

Crossrefs

Cf. A155085.

Programs

Mathematica

Select[Range[701100],IntegerQ[Surd[DivisorSigma[1,#]+#,3]]&] (* Harvey P. Dale, Oct 22 2023 *)

PARI

isok(n) = ispower(sigma(n) + n, 3); \\ Michel Marcus, Jan 22 2014

Extensions

More terms from Michel Marcus, Jan 22 2014