



That's what some brief experiments suggest though.

1+10^4+10^18+10^201 == 1000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001000000000000010001 is the largest one I found. Also I don't notice any patterns, e.g. here in the first 200 such primes







and here are the first 254 primes with nonzero digits {1,2,1}







the largest found is

1+2*10^14+10^201 == 1000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000200000000000001 Does anyone else have any primes which don't seem like they should be prime? The more extreme the better. How small can a description of a large prime number be? There are the Fermat primes 2^n-1 for certain n, and in base 2 these are a sequence of ones. In base 10, if you have just zeros and two ones, then the only primes of that form are 11 and 101. If there are three ones then it is divisible by three. But what about four ones? It seems wrong to me that there might be an unbounded number of such primes.That's what some brief experiments suggest though.is the largest one I found. Also I don't notice any patterns, e.g. here in the first 200 such primesand here are the first 254 primes with nonzero digits {1,2,1}the largest found isDoes anyone else have any primes which don't seem like they should be prime? The more extreme the better.