From: rcs@xmission.com

3 -> 13: My notion was that leading 0s are ruled out, so each size is a separate problem space. With this restriction, I think all the two digit primes are connected, and all the three digit primes are connected.

From: Warut Roonguthai <warut822@gmail.com>

I found that all the 4-digit primes are connected even under the restriction, and this is also true for the 5-digit case.

I think all the one-digit primes are connected!! --Steve