Confusion about Wall-sun-sun primes Here :
https://en.wikipedia.org/wiki/Table_of_congruences
$691$ is mentioned as the smallest Wall-sun-sun prime although no Wall-sun-sun prime is known. Apparently, this is a typo.

Does anyone have an idea how this typo could emerge ? Is there a property that $691$ has which could have led to this typo ?


It may have been confused with the first Lychrel number, which is $196$ with its associated palimdrom prime $691$. But this is pure speculation. See sequence A023108 in OEIS.
