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Super Unitary Perfect Number


An integer n is called a super unitary perfect number if

 sigma^*(sigma^*(n))=2n,

where sigma^*(n) is the unitary divisor function. The first few are 2, 9, 165, 238, 1640, ... (OEIS A038843). It is not known if there exist any odd super unitary perfect numbers other than 9 and 165 (Yamada 2008).


See also

Unitary Divisor Function, Unitary Perfect Number

This entry contributed by Yasutoshi Kohmoto

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References

Sloane, N. J. A. Sequence A038843 in "The On-Line Encyclopedia of Integer Sequences."Yamada, T. "Unitary Super Perfect Numbers." Math. Pannon. 19, 37-47, 2008.

Referenced on Wolfram|Alpha

Super Unitary Perfect Number

Cite this as:

Kohmoto, Yasutoshi. "Super Unitary Perfect Number." From MathWorld--A Wolfram Web Resource, created by Eric W. Weisstein. https://mathworld.wolfram.com/SuperUnitaryPerfectNumber.html

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