A sous-double is a 3-multiperfect number 
. Six sous-doubles are known (120,
672, 523776, 459818240, 1476304896, and 51001180160; OEIS A005820;
Broughan and Zhou 2010, p. 2), and these are believed to comprise all sous-doubles.
Sous-Double
See also
Multiperfect Number, Sous-TripleExplore with Wolfram|Alpha
References
Broughan, K. A. and Zhou, Q. "Divisibility by 3 of Even Multiperfect Numbers of Abundancy 3 and 4." J. Integer Seq. 13, Art. 10.1.5, 2010. https://cs.uwaterloo.ca/journals/JIS/VOL13/Broughan/broughan17d.html.Sloane, N. J. A. Sequence A005820/M5376 in "The On-Line Encyclopedia of Integer Sequences."Referenced on Wolfram|Alpha
Sous-DoubleCite this as:
Weisstein, Eric W. "Sous-Double." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/Sous-Double.html