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Divisibility

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Unsolved Problems in Number Theory

Part of the book series: Unsolved Problems in Intuitive Mathematics ((1605,volume 1))

Abstract

We will denote by d(n) the number of positive divisors of n, by σ(n) the sum of those divisors, and by σ k (n) the sum of their kth powers, so that σ 0(n) = d(n) and σ 1(n) = σ(n). We use s(n) for the sum of the aliquot parts of n, i.e., the positive divisors of n other than n itself, so that s(n) = σ(n) − n.

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    Richard K. Guy

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Guy, R.K. (1981). Divisibility. In: Unsolved Problems in Number Theory. Unsolved Problems in Intuitive Mathematics, vol 1. Springer, New York, NY. https://doi.org/10.1007/978-1-4757-1738-9_3

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