A219036 Numbers n such that sigma(n) - tau(n) is a perfect number.

7, 21, 25, 29, 246, 286, 2688, 4062, 33550337, 4294934526, 5658405646, 5726153206, 5726306566, 6987790105, 7533178601

Offset

1,1

Links

Table of n, a(n) for n=1..15.

Formula

Numbers n such that sigma(n) - tau(n) is a perfect number.

Mathematica

perfectQ[n_] := DivisorSigma[1, n] == 2*n; Select[Range[100000], perfectQ[DivisorSigma[1, #] - DivisorSigma[0, #]] &] (* T. D. Noe, Nov 13 2012 *)

Crossrefs

Cf. A000396 (perfect numbers).

Sequence in context: A200935 A097182 A058525 * A063469 A155131 A160890

Adjacent sequences: A219033 A219034 A219035 * A219037 A219038 A219039

Keyword

nonn

Author

Zdenek Cervenka, Nov 13 2012

Extensions

25 and 29 added by T. D. Noe, Nov 13 2012

a(10)-a(15) from Donovan Johnson, Nov 13 2012

Status

approved