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A078543 Balanced refactorable numbers. 2


%S 1,2,12,56,248,12192,28896,60960,61344,66528,86304,94944,129504,

%T 133920,140448,182880,201924,207264,242316,282720,408672,416640,

%U 426720,429408,604128,664608,671760,776736,792480,854496,862752,906528

%N Balanced refactorable numbers.

%H Amiram Eldar, <a href="/A078543/b078543.txt">Table of n, a(n) for n = 1..10000</a> (calculated using data from Jud McCranie, terms 1..500 from Donovan Johnson)

%e n=56: tau(56)=8, sigma(56)=120, phi(56)=24, q1=120/24=5 for balancedness, q2=56/8=7 for refactorability.

%t Do[s=DivisorSigma[1, n]/EulerPhi[n]; If[ !IntegerQ[s]&&!PrimeQ[n], Print[n]], {n, 1, 256}]

%Y Intersection of A033950 and A020492.

%Y Cf. A078538, A078539, A078540.

%K nonn

%O 1,2

%A _Labos Elemer_, Dec 04 2002

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Last modified September 24 09:10 EDT 2021. Contains 347630 sequences. (Running on oeis4.)