- $6, 12, 18, 20, 24, 28, 30, \ldots$
Also defined as
- A semiperfect number is a positive integer which is equal to the sum of some, but not all of its aliquot parts.
It is possible this is a mistake in 1997: David Wells: Curious and Interesting Numbers (2nd ed.), as the author of this page has not been able to corroborate this definition with any sources elsewhere.
Also known as
Some sources use a hyphen: semi-perfect number.
The term pseudoperfect is also often seen.
- Results about semiperfect numbers can be found here.
- 1986: David Wells: Curious and Interesting Numbers ... (previous) ... (next): $20$
- 1997: David Wells: Curious and Interesting Numbers (2nd ed.) ... (previous) ... (next): $20$
- Weisstein, Eric W. "Pseudoperfect Number." From MathWorld--A Wolfram Web Resource. http://mathworld.wolfram.com/PseudoperfectNumber.html