Primes whose first and last number is 3: Difference between revisions
Primes whose first and last number is 3 (view source)
Revision as of 19:24, 28 July 2021
, 2 years agoAdded Sidef
m (→{{header|REXX}}: changed a comment, elided the use of the prime semaphores.) |
(Added Sidef) |
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Found 33 numbers
done...
</pre>
=={{header|Sidef}}==
<lang ruby>func numbers_with_edges(upto, base = 10, s = [3]) {
Enumerator({|callback|
callback(s.digits2num(base))
for k in (0 .. base**(upto.len(base) - 2*s.len)) {
Inf.times { |j|
var d = (s + k.digits(base) + j.of(0) + s)
var n = d.digits2num(base)
(n <= upto) ? callback(n) : break
}
}
})
}
with (4e3) { |n|
var list = numbers_with_edges(n).grep{.is_prime}.sort
say "There are #{list.len} primes <= #{n.commify} which begin and end in 3:"
list.each_slice(10, {|*a| say a.map { '%5s' % _ }.join(' ') })
}
with (1e6) {|n|
var count = numbers_with_edges(n).grep{.is_prime}.len
say "\nThere are #{count} primes <= #{n.commify} which begin and end in 3"
}</lang>
{{out}}
<pre>
There are 33 primes <= 4,000 which begin and end in 3:
3 313 353 373 383 3023 3083 3163 3203 3253
3313 3323 3343 3373 3413 3433 3463 3533 3583 3593
3613 3623 3643 3673 3733 3793 3803 3823 3833 3853
3863 3923 3943
There are 2251 primes <= 1,000,000 which begin and end in 3
</pre>
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