65970domain: NAppears in sequencesa(n) cannot be prefixed or followed by any digit to form a prime ('empty' prefixes allowed).at n=19A032736a(n) cannot be prefixed or followed by any digit to form a prime ('empty' prefixes and suffixes are allowed).at n=13A032738Numbers n such that 173*2^n-1 is prime.at n=31A050838