Journal of Integer Sequences, Vol. 28 (2025), Article 25.4.5

Determining all Biunitary Triperfect Numbers of a Certain Form


Tomohiro Yamada
Center for Japanese Language and Culture
Osaka University
562-8678, 3-5-10, Sembahigashi
Minoo, Osaka
Japan

Abstract:

A divisor d of an integer N is called a unitary divisor of N if d and N/d are relatively prime and a biunitary divisor of N if d and N/d have no common unitary divisor except 1. An integer N is called a biunitary triperfect number if the sum σ**(N) of biunitary divisors of N is equal to 3N. We show that 2160 is the only biunitary triperfect number divisible by 27 = 33.


Full version:  pdf,    dvi,    ps,    latex    


(Concerned with sequences A000396 A005820 A038843 A188999 A189000 A318175 A318781.)


Received June 27 2025; revised version received August 6 2025. Published in Journal of Integer Sequences, August 6 2025.


Return to Journal of Integer Sequences home page