On: Prime numbers so memorable that people hunt for them

[Retric]

> Sloane calls them “memorable” primes

Excluding 11 seems arbitrary here.

[DerekL → Retric]

No, that doesn't fit the pattern. The number in the middle can't be repeated.

[Retric → DerekL]

That’s how it’s excluded, not why we should care about the pattern being exactly that formula.

[DerekL → Retric]

Sure, you could also look for primes of the form 123…(n-1)n⋅n(n-1)…321.

[oneshtein → Retric]

11

131

13331

100000000000000000000333000000000000000000001 (20 zeroes on both sides)

11111111111111111111111 (1©23)