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,
and a more sophisticated one that is well-suited for generating very large numbers of such primes,
as illustrated by counting the number less than 10^
For a suitable implementation of `is_prime` as used here, see [[Erd%C5%91s-primes#jq]].
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end;
# palindromes with an even number of digits are divisible by 11
range(1;infinite) as $mid▼
▲ range(1;infinite;2) as $mid
| ("1", "3", "7", "9") as $start
| $start + middle($mid) + $start ;
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Number of palindromic primes <= 1000000000: 5953
</pre>▼
Number of palindromic primes <= 10000000000: 5953
▲</pre>
=={{header|Julia}}==
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