Sphenic numbers: Difference between revisions
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The 5,000th sphenic triplet is (918005, 918006, 918007).</pre>
=={{header|Ruby}}==
<syntaxhighlight lang="ruby">require 'prime'
class Integer
def sphenic?
pd = prime_division
pd.size==3 && pd.map(&:last).all?{|exp| exp == 1}
end
end
sphenics = (1..).lazy.select(&:sphenic?)
n = 1000
puts "Sphenic numbers less than #{n}:"
p sphenics.take_while{|s| s < n}.to_a
n = 10_000
puts "\nSphenic triplets less than #{n}:"
sps = sphenics.take_while{|s| s < n}.to_a
sps.each_cons(3).select{|a, b, c| a + 2 == c}.each{|ar| p ar}
n = 1_000_000
sphenics_below10E6 = sphenics.take_while{|s| s < n}.to_a
puts "\nThere are #{sphenics_below10E6.size} sphenic numbers below #{n}."
target = sphenics_below10E6[200_000-1]
puts "\nThe 200000th sphenic number is #{target} with factors #{target.prime_division.map(&:first)}."
triplets = sphenics_below10E6.each_cons(3).select{|a,b,c|a+2 == c}
puts "\nThe 5000th sphenic triplet is #{triplets[4999]}."</syntaxhighlight>
{{out}}
<pre>Sphenic numbers less than 1000:
[30, 42, 66, 70, 78, 102, 105, 110, 114, 130, 138, 154, 165, 170, 174, 182, 186, 190, 195, 222, 230, 231, 238, 246, 255, 258, 266, 273, 282, 285, 286, 290, 310, 318, 322, 345, 354, 357, 366, 370, 374, 385, 399, 402, 406, 410, 418, 426, 429, 430, 434, 435, 438, 442, 455, 465, 470, 474, 483, 494, 498, 506, 518, 530, 534, 555, 561, 574, 582, 590, 595, 598, 602, 606, 609, 610, 615, 618, 627, 638, 642, 645, 646, 651, 654, 658, 663, 665, 670, 678, 682, 705, 710, 715, 730, 741, 742, 754, 759, 762, 777, 782, 786, 790, 795, 805, 806, 814, 822, 826, 830, 834, 854, 861, 874, 885, 890, 894, 897, 902, 903, 906, 915, 935, 938, 942, 946, 957, 962, 969, 970, 978, 986, 987, 994]
Sphenic triplets less than 10000:
[1309, 1310, 1311]
[1885, 1886, 1887]
[2013, 2014, 2015]
[2665, 2666, 2667]
[3729, 3730, 3731]
[5133, 5134, 5135]
[6061, 6062, 6063]
[6213, 6214, 6215]
[6305, 6306, 6307]
[6477, 6478, 6479]
[6853, 6854, 6855]
[6985, 6986, 6987]
[7257, 7258, 7259]
[7953, 7954, 7955]
[8393, 8394, 8395]
[8533, 8534, 8535]
[8785, 8786, 8787]
[9213, 9214, 9215]
[9453, 9454, 9455]
[9821, 9822, 9823]
[9877, 9878, 9879]
There are 206964 sphenic numbers below 1000000.
The 200000th sphenic number is 966467 with factors [17, 139, 409].
The 5000th sphenic triplet is [918005, 918006, 918007].
</pre>
=={{header|Wren}}==
{{libheader|Wren-math}}
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