Henry Ernest Dudeney/Puzzles and Curious Problems/88 - Digital Progression/Historical Note

== Historical Note on by : $88$ - Digital Progression == informs that subsequent to 's $4$ examples,  reported on $760$ such progressions in his  from $1952$.

He also found that in addition to $456$ and its permutations, the middle number may be any of the permutations of $258$, $267$, $348$ and $357$.