Find squares n where n+1 is prime: Difference between revisions

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(Add CLU)
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</pre>
</pre>


=={{header|CLU}}==
<lang clu>isqrt = proc (s: int) returns (int)
x0: int := s/2
if x0=0 then return(s) end
x1: int := (x0 + s/x0)/2
while x1 < x0 do
x0 := x1
x1 := (x0 + s/x0)/2
end
return(x0)
end isqrt

sieve = proc (n: int) returns (array[int])
prime: array[bool] := array[bool]$fill(2,n-1,true)
primes: array[int] := array[int]$predict(1,isqrt(n))
for p: int in int$from_to(2,isqrt(n)) do
if prime[p] then
for c: int in int$from_to_by(p*p,n,p) do
prime[c] := false
end
end
end
for p: int in array[bool]$indexes(prime) do
if prime[p] then array[int]$addh(primes,p) end
end
return(primes)
end sieve

is_square = proc (n: int) returns (bool)
return(isqrt(n) ** 2 = n)
end is_square

start_up = proc ()
po: stream := stream$primary_output()
primes: array[int] := sieve(1000)
for prime: int in array[int]$elements(primes) do
n: int := prime-1
if is_square(n) then stream$puts(po, int$unparse(n) || " ") end
end
end start_up</lang>
{{out}}
<pre>1 4 16 36 100 196 256 400 576 676</pre>
=={{header|F_Sharp|F#}}==
=={{header|F_Sharp|F#}}==
This task uses [http://www.rosettacode.org/wiki/Extensible_prime_generator#The_functions Extensible Prime Generator (F#)]
This task uses [http://www.rosettacode.org/wiki/Extensible_prime_generator#The_functions Extensible Prime Generator (F#)]
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1 4 16 36 100 196 256 400 576 676
1 4 16 36 100 196 256 400 576 676
</pre>
</pre>

=={{header|Fermat}}==
=={{header|Fermat}}==
<lang fermat>!!1;
<lang fermat>!!1;
Retrieved from "https://rosettacode.org/wiki/Find_squares_n_where_n%2B1_is_prime"