Palindromic primes: Difference between revisions
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In this entry, we define both a naive generate-and-test generator of the palindromic primes, |
In this entry, we define both a naive generate-and-test generator of the palindromic primes, |
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and a more sophisticated one that is well-suited for generating very large numbers of such primes, |
and a more sophisticated one that is well-suited for generating very large numbers of such primes, |
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as illustrated by counting the number less than 10^ |
as illustrated by counting the number less than 10^10. |
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For a suitable implementation of `is_prime` as used here, see [[Erd%C5%91s-primes#jq]]. |
For a suitable implementation of `is_prime` as used here, see [[Erd%C5%91s-primes#jq]]. |
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end; |
end; |
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# palindromes with an even number of digits are divisible by 11 |
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| ("1", "3", "7", "9") as $start |
| ("1", "3", "7", "9") as $start |
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| $start + middle($mid) + $start ; |
| $start + middle($mid) + $start ; |
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Number of palindromic primes <= 1000000000: 5953 |
Number of palindromic primes <= 1000000000: 5953 |
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Number of palindromic primes <= 10000000000: 5953 |
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=={{header|Julia}}== |
=={{header|Julia}}== |
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