Cubic special primes: Difference between revisions
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2531 2539 3539 3547 4547 5059 10891 12619 13619 13627
13691 13907 14419
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=={{header|Lua}}==
<syntaxhighlight lang="lua">
do -- find a sequence of primes where the members differ by a cube
local maxPrime = 15000
-- sieve the primes to maxPrime
local isPrime = {}
for i = 1, maxPrime do isPrime[ i ] = i % 2 ~= 0 end
isPrime[ 1 ] = false
isPrime[ 2 ] = true
for s = 3, math.floor( math.sqrt( maxPrime ) ), 2 do
if isPrime[ s ] then
for p = s * s, maxPrime, s do isPrime[ p ] = false end
end
end
-- construct a table of cubes, we will need at most the cube root of maxPrime
local cube = {}
for i = 1, math.floor( ( maxPrime ^ ( 1 / 3 ) ) ) do cube[ i ] = i * i * i end
-- find the prime sequence
io.write( "2" )
local p = 2
while p < maxPrime do
-- find a prime that is p + a cube
local q, i = 0, 1
repeat
q, i = p + cube[ i ], i + 1
until q > maxPrime or isPrime[ q ]
if q <= maxPrime then io.write( " ", q ) end
p = q
end
io.write( "\n" )
end
</syntaxhighlight>
{{out}}
<pre>
2 3 11 19 83 1811 2027 2243 2251 2467 2531 2539 3539 3547 4547 5059 10891 12619 13619 13627 13691 13907 14419
</pre>
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