Numbers whose count of divisors is prime: Difference between revisions
Numbers whose count of divisors is prime (view source)
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Found 79 such integers (16 under 1,000).
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=={{header|J}}==
To find the divisors of a number we can use any of the implementations defined at in the [[Factors_of_an_integer#J|Factors of an integer]] task: <code>foi</code>, <code>factrs</code>, <code>factrst</code>, <code>factorsOfNumber</code> or <code>factors</code>. Here, we will use <code>factors</code> as it's the most efficient:
<syntaxhighlight lang=J>
(#~ (2&< * 1&p:)@#@factors"0) }. i. 100000
4 9 16 25 49 64 81 121 169 289 361 529 625 729 841 961 1024 1369 1681 1849 2209 2401 2809 3481 3721 4096 4489 5041 5329 6241 6889 7921 9409 10201 10609 11449 11881 12769 14641 15625 16129 17161 18769 19321 22201 22801 24649 26569 27889 28561 29929 32041 32761 36481 37249 38809 39601 44521 49729 51529 52441 54289 57121 58081 59049 63001 65536 66049 69169 72361 73441 76729 78961 80089 83521 85849 94249 96721 97969
</syntaxhighlight>
(Note that we first conditioned J's environment to show longer lines, using [https://www.jsoftware.com/help/dictionary/dx009.htm#36 <code>9!:37(10*9!:36'')</code>].)
=={{header|jq}}==
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