OFFSET
1,1
COMMENTS
A002093(848) < a(9) <= 1155321467378283328. - Donovan Johnson, Nov 03 2011
MATHEMATICA
perfect = {6, 28, 496, 8128, 33550336, 8589869056, 137438691328}; Select[Range[10000], MemberQ[perfect, DivisorSigma[0, #] + DivisorSigma[1, #]] &] (* T. D. Noe, Nov 03 2011 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Jeff Kruse, Oct 26 2011
EXTENSIONS
a(8) from Donovan Johnson, Nov 03 2011
STATUS
approved