# “Strange” prime number" [closed]

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?

Pierre MATSUMI

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## closed as off topic by Suvrit, Franz Lemmermeyer, Igor Rivin, Zev Chonoles, Felipe VolochOct 5 '11 at 13:42

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17*43 == 731 is NOT a prime!! – Suvrit Oct 5 '11 at 13:22
This looks like spam to me, because very of the numbers mentioned are prime (they just look primy, but are not!) --- please clarify – Suvrit Oct 5 '11 at 13:25
Even if the numbers were prime, this is more recreational mathematics than research. – Igor Rivin Oct 5 '11 at 13:37