4 Positive Integers in Arithmetic Sequence which have Same Euler Phi Value/Mistake

Source Work

 * The Dictionary
 * $72$
 * $72$


 * The Dictionary
 * $72$
 * $72$

Mistake

 * $\map \phi {72} = \map \phi {78} = \map \phi {84} = \map \phi {90} = 24$. This is the smallest set of four numbers in arithmetical progression whose $\phi$ values are equal. The next two $4$-term arithmetical progressions with equal $\phi$ values start at $216$ and $76,236$ and each has a common difference, $6$.

Correction
The last one of those should say $76,326$.