O'Halloran numbers: Difference between revisions
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Here, we use [[Combinations_with_repetitions#J|combinations with repetitions]] to generate the various relevant cuboid side lengths. Then we multiply all three pairs of these side length combinations and sum the pairs. Then we remove these sums from the sequence 3..500, and finally we multiply the remaining 16 values by 2.
=={{header|jq}}==
{{Works with|jq}}
'''Also works with jaq and with gojq, the Go implementation of jq'''
<syntaxhighlight lang=jq>
# Emit a stream of possible cuboid areas less than or equal to the specified limit,
# $maxarea, which should be an even integer.
def cuboid_areas($maxarea):
maxarea as $maxarea
# min area per face is 1 so if total area is $maxarea, the max dimension is ($maxarea-4)/2
| ($maxarea/2) as $halfmax
| ($halfmax - 2) as $max
| foreach range(1; 1+$max) as $i (null;
label $loopj
# By symmetry, we can assume i < j < k
| foreach range($i; 1+$max) as $j (.;
($i*$j) as $ij
| if $ij + 2 > $halfmax then break $loopj else . end
| label $loopk
| foreach range($j; 1+$max) as $k (.;
($ij + $i*$k + $j*$k) as $total
| if $total > $halfmax then break $loopk
else 2 * $total
end) ) );
1000 as $n
| "Even integers greater than 6 but less than \($n) that cannot be cuboid surface areas:",
[range(6;$n;2)] - [cuboid_areas($n-2)]
</syntaxhighlight>
<pre>
Even integers greater than 6 but less than 1000 that cannot be cuboid surface areas:
[8,12,20,36,44,60,84,116,140,156,204,260,380,420,660,924]
</pre>
=={{header|Julia}}==
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