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A219036
Numbers n such that sigma(n) - tau(n) is a perfect number.
0
7, 21, 25, 29, 246, 286, 2688, 4062, 33550337, 4294934526, 5658405646, 5726153206, 5726306566, 6987790105, 7533178601
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
Cf. A000396 (perfect numbers).
Sequence in context: A200935 A097182 A058525 * A063469 A155131 A160890
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