612014161920
domain: N
Appears in sequences
- Nonunitary doubly perfect numbers: the sum of the nonunitary divisors of n is 2n; i.e., sigma(n) - usigma(n) = 2n.at n=11A064592
- Numbers k such that there is a proper divisor d of k satisfying sigma(d)=k.at n=25A081756
- Numbers n such that psi(n) is the sum of proper divisors of n where psi(n) = A001615(n).at n=10A291209
- Sum of divisors of the multiply-perfect numbers.at n=25A307741