Smallest number k such that k+2^m is composite for all m less than k: Difference between revisions
Smallest number k such that k+2^m is composite for all m less than k (view source)
Revision as of 22:09, 13 March 2023
, 1 year ago→{{header|Ruby}}: Add Ruby
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<pre>773 2131 2491 4471 5101</pre>
=={{header|Ruby}}==
<syntaxhighlight lang="ruby" line>require 'openssl'
a = (1..).step(2).lazy.select do |k|
next if k == 1
(1..(k-1)).none? {|m| OpenSSL::BN.new(k+(2**m)).prime?}
end
p a.first 5</syntaxhighlight>
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<pre>[773, 2131, 2491, 4471, 5101]</pre>
=={{header|Wren}}==
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