1111111111111111111

This number is a prime.

                                                        111111111 1111111111

Just showing those entries submitted by 'Dobb': (Click here to show all)

      1 1 1
     1 1 1 1
    1 1 1 1 1
     1 1 1 1
      1 1 1

A repunit hex-congruent prime in bases 11 and 12. [Dobb]