Let p = a_1a_2.. a_n be a prime number.

Definition: p is "Strange" if p remains prime after deletion of any a_i.

Example 1: 731. If you delete 7 => 31 (prime), if you delete 3 => 71 (prime) if you delete 1 => 73 (prime).

Example 2: 3071. If you delete 3 => 71 (prime), if you delete 0 => 371 (prime) if you delete 7 => 301 (prime), if you delete 1 => 307 (prime).

Question: Are there infinitely may strange prime?

Please tell me anything.

Pierre MATSUMI