OFFSET
1,1
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
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