Numbers whose count of divisors is prime: Difference between revisions
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Drkameleon (talk | contribs) (added Arturo) |
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=={{header|Ruby}}== |
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Testing squares only, according to observation on the discussion page. |
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<syntaxhighlight lang="ruby">require 'prime' |
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def tau(n) = n.prime_division.inject(1){|res, (d, exp)| res *= exp+1} |
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res = (1..Integer.sqrt(100_000)).filter_map{|n| sqr = n*n; sqr if tau(sqr).prime? } |
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res.each_slice(10){|slice| puts "%10d"*slice.size % slice}</syntaxhighlight> |
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{{out}} |
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<pre> 4 9 16 25 49 64 81 121 169 289 |
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361 529 625 729 841 961 1024 1369 1681 1849 |
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2209 2401 2809 3481 3721 4096 4489 5041 5329 6241 |
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6889 7921 9409 10201 10609 11449 11881 12769 14641 15625 |
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16129 17161 18769 19321 22201 22801 24649 26569 27889 28561 |
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29929 32041 32761 36481 37249 38809 39601 44521 49729 51529 |
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52441 54289 57121 58081 59049 63001 65536 66049 69169 72361 |
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73441 76729 78961 80089 83521 85849 94249 96721 97969 |
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</pre> |
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=={{header|Sidef}}== |
=={{header|Sidef}}== |
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<syntaxhighlight lang="ruby">var limit = 100_000 |
<syntaxhighlight lang="ruby">var limit = 100_000 |