Integers whose Ratio between Divisor Sum and Phi is Square/Examples/714
Jump to navigation
Jump to search
Example of Integer whose Ratio between Divisor Sum and Phi is Square
\(\ds \map \phi {714}\) | \(=\) | \(\ds 192\) | $\phi$ of $714$ | |||||||||||
\(\ds \map {\sigma_1} {714}\) | \(=\) | \(\ds 1728\) | $\sigma_1$ of $714$ | |||||||||||
\(\ds \map {\sigma_1} {714} / \map \phi {714}\) | \(=\) | \(\ds 1728 / 192\) | ||||||||||||
\(\ds \) | \(=\) | \(\ds 9\) | ||||||||||||
\(\ds \) | \(=\) | \(\ds 3^2\) |
$\blacksquare$
Sources
- 1974: C. Nelson, D.E. Penney and C. Pomerance: 714 and 715 (J. Recr. Math. Vol. 7, no. 2: pp. 87 – 89)
- 1986: David Wells: Curious and Interesting Numbers ... (previous) ... (next): $714$
- 1997: David Wells: Curious and Interesting Numbers (2nd ed.) ... (previous) ... (next): $714$