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Strictly non-palindromic numbers (Posted on 2018-02-18) Difficulty: 3 of 5
Definition: Strictly non-palindromic number or SNP number n is a number not palindromic in any base b with 2 ≤ b ≤ n-2.

Equipped only with the above definition you are asked to perform the following tasks:
1. Show that 47 is a SNP number.
2. Write down the 1st 7 members of an increasing sequence of SNP numbers.
3. Explain the reason for defining b=n-2 as the upper limit.
4. Prove that all SNP numbers above 6 are prime, but not all primes are SNP numbers.

No Solution Yet Submitted by Ady TZIDON    
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Comments: ( Back to comment list | You must be logged in to post comments.)
Hints/Tips re: Task 4 Comment 3 of 3 |
(In reply to Task 4 by Jer)

You prefer   "...that the list should start 1,2,3,4,6...

Well,  you may say    0,1,2,3,4,6...
OEIS  quotes two lists -   one starting 4,6.. etc   and  the other  0,1,2,3,4,6...
It depends how one considers the condition "any base b
with 2 ≤ b ≤ n-2. 

  Posted by Ady TZIDON on 2018-02-18 14:28:28
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