Geodesic
The 4-Nicol numbers having five different prime divisors
Journal of integer sequences, Tome 14 (2011) no. 7.

Voir la notice de l'article provenant de la source Electronic Library of Mathematics

Summary: A positive integer $ n$ is called a Nicol number if $ n\mid \varphi(n)+\sigma(n)$, and a $t$-Nicol number if $ \varphi(n)+\sigma(n)=tn$. In this paper, we show that if $ n$ is a 4-Nicol number that has five different prime divisors, then $ n=2^{\alpha_{1}}\cdot 3\cdot 5^{\alpha_{3}}\cdot p^{\alpha_{4}}\cdot q^{\alpha_{5}}$, or $ n=2^{\alpha_{1}}\cdot 3\cdot 7^{\alpha_{3}}\cdot p^{\alpha_{4}}\cdot q^{\alpha_{5}}$ with $ p\leq 29$.
Classification : 11A25
Keywords: nicol number, Euler's totient function 
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     author = {Jin, Qiao-Xiao and Tang, Min},
     title = {The {4-Nicol} numbers having five different prime divisors},
     journal = {Journal of integer sequences},
     publisher = {mathdoc},
     volume = {14},
     number = {7},
     year = {2011},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/JIS_2011__14_7_a6/}
}
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Jin, Qiao-Xiao; Tang, Min. The 4-Nicol numbers having five different prime divisors. Journal of integer sequences, Tome 14 (2011) no. 7. http://geodesic.mathdoc.fr/item/JIS_2011__14_7_a6/