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Kravitz Conjecture


The Kravitz conjecture asserted that no positive integer has abundance equal to a positive odd number that is a square number (Guy 2004). Write A(n)=sigma(n)-2n, where sigma(n) is the divisor function. The first few numbers whose abundance absolute values are odd squares (excluding the trivial cases of powers of 2) are 98, 2116, 4232, 49928, 80656, 140450, 550564, 729632, ... (OEIS A188484).

The conjecture is false with smallest counterexample

A(550564)=41209
(1)
=203^2,
(2)

and first few counterexamples given by 550564, 15038884, 57365476, ... (OEIS A188486).


See also

Abundance

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References

Guy, R. K. Unsolved Problems in Number Theory, 3rd ed. New York: Springer-Verlag, 2004.Sloane, N. J. A. Sequences A188484 and A188486 in "The On-Line Encyclopedia of Integer Sequences."

Referenced on Wolfram|Alpha

Kravitz Conjecture

Cite this as:

Weisstein, Eric W. "Kravitz Conjecture." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/KravitzConjecture.html

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