A116013 n+sigma(n)+sigma(sigma(n)) is a cube.

517, 1403, 2467, 28265, 28580, 49888, 52396, 77429, 81099, 290936, 319600, 394731, 462803, 555543, 601943, 617716, 633065, 634808, 720401, 775669, 884835, 894024, 1077432, 1089360, 1170136, 1178152, 1191789, 1209357

Offset

1,1

Links

Table of n, a(n) for n=1..28.

Example

1403+sigma(1403)+sigma(sigma(1403))=19^3.

Mathematica

scQ[n_]:=Module[{c=DivisorSigma[1, n]}, IntegerQ[(n+c+DivisorSigma[1, c]) ^ (1/3)]]; Select[Range[1300000], scQ] (* Harvey P. Dale, Dec 17 2012 *)

Crossrefs

Cf. A116012, A116014, A116015.

Sequence in context: A232574 A282753 A168188 * A225913 A233054 A235305

Adjacent sequences: A116010 A116011 A116012 * A116014 A116015 A116016

Keyword

nonn

Author

Giovanni Resta, Feb 13 2006

Status

approved