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User:M. F. Hasler/Work in progress/Practical numbers
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Related sequences & pages:
- A005153 Practical numbers: positive integers n such that every k <= sigma(n) is a sum of distinct divisors of n. Also called panarithmic numbers.
- A007620 Numbers n such that every k <= n is a sum of proper divisors of n (for n>1). (subsequence of A005153)
Zhi-Wei Sun's sequences and conjectures:
- Sandwiches:
- A210479 List of primes p with p-1 and p+1 both practical.
- Others: