15000...30001 (74-digits)

This number is a prime.

                                                                        1500
0000000000 0001300000 0000000011 0000000000 0900000000 0700000005 0000030001

In this prime number, the 15 is followed by 15 zeros, the 13 by 13, the 11 by 11, and so on. [Hartley]