A219179 Numbers n such that sigma(n)/tau(n) is a perfect number.

11, 14, 15, 91, 92, 132, 140, 991, 1891, 3525, 3792, 4025, 4650, 5775, 6384, 45847, 78337, 99904, 105664, 180544, 133152769, 134176771, 227512999, 233016679, 451443979, 865079296, 1478127616, 1509765120, 1585188864, 1660973056, 1793101824, 3063803904

Offset

1,1

Links

Table of n, a(n) for n=1..32.

Mathematica

perfectQ[n_] := DivisorSigma[1, n] == 2*n; Select[Range[10000], perfectQ[DivisorSigma[1, #] / DivisorSigma[0, #]] &] (* T. D. Noe, Nov 13 2012 *)

Crossrefs

Subsequence of A003601.

Cf. A000396 (perfect numbers).

Sequence in context: A061743 A038630 A239935 * A221281 A025058 A025060

Adjacent sequences: A219176 A219177 A219178 * A219180 A219181 A219182

Keyword

nonn

Author

Zdenek Cervenka, Nov 13 2012

Extensions

a(21)-a(32) from Donovan Johnson, Nov 13 2012

Status

approved