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Old 2014-11-14, 23:32   #1
Batalov
 
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Smile Palindrome primes (a.k.a. Elementary S03E03 "Just a Regular Irregular")

Last night's Elementary was a bit of a disappointment... because on one superficial level, it dealt with ... (gasp) math. Again, I might add.

One of the premises (without giving away any clues) was the existence of a super-mysterious devilish prime number that was palindromic, 666 in the middle, bracketed on both sides by a row of zeroes and ones at the ends. Iirc the one they used had thirteen zeroes.

Aw, big deal! Puzzle: find more of these.

For bonus points, reminds us the fancy name that they used for describing this number. It escapes me.
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Old 2014-11-15, 00:16   #2
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I'll start. I spy eight of them, the largest currently being this.

Rudolf Ondrejka called these "beastly palindromic primes".

Last fiddled with by Batalov on 2014-11-15 at 00:55
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Old 2014-11-15, 02:08   #3
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Belphegor's Prime
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Old 2014-11-15, 03:01   #4
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Ah. Exactly right.
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Old 2014-11-15, 03:41   #5
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Sorry, I didn't have anything else to add. I won't even try to find another one of these primes, but I do wonder if we can find one of these primes that is also prime when the 6s are 9s (like turning the number 180 degrees). Is that even possible? None of the ones on that list you posted qualify.

Last fiddled with by Jayder on 2014-11-15 at 03:53
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Old 2014-11-15, 05:21   #6
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There are 16661 and 19991 with both being prime.
Does it has to have zeroes?
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Old 2014-11-15, 05:35   #7
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Oh yeah! Thanks LaurV. I did see that one but I forgot about it.
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Old 2014-11-15, 06:37   #8
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Well, then, allow me to present you with the largest currently known palindrome prime.
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Old 2014-11-15, 06:42   #9
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Quote:
Originally Posted by Batalov View Post
Well, then, allow me to present you with the largest currently known palindrome prime.
Somehow I was expecting this... .
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Old 2014-11-15, 09:50   #10
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Beautiful! Totally!
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Old 2014-11-16, 10:28   #11
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Quote:
Originally Posted by Jayder View Post
Sorry, I didn't have anything else to add. I won't even try to find another one of these primes, but I do wonder if we can find one of these primes that is also prime when the 6s are 9s (like turning the number 180 degrees). Is that even possible? None of the ones on that list you posted qualify.
Well, why not?

These constitute a new sequence (the upside-down Belphegor's Primes). Pending.

Allow me to present to you the largest currently known palindrome prime. No, it only looks like a tautology; it's not.
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