Find squares n where n+1 is prime: Difference between revisions
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integer i2, toNext;
toNext := i2 := 4; % note: ( 2n + 2 )^2 - 2n^2 = 8n + 4 %
if isPrime( i2 + 1 ) then writeon( i_w := 1, s_w := 0, " ", i2 );
toNext := toNext + 8;
i2 := i2 + toNext
end
end
end.
Line 471:
</pre>
=={{header|EasyLang}}==
<syntaxhighlight>
fastfunc isprim num .
i = 2
while i <= sqrt num
if num mod i = 0
return 0
.
i += 1
.
return 1
.
n0 = 1
repeat
n = n0 * n0
until n >= 1000
if isprim (n + 1) = 1
write n & " "
.
n0 += 1
.
</syntaxhighlight>
{{out}}
<pre>
1 4 16 36 100 196 256 400 576 676
</pre>
=={{header|F_Sharp|F#}}==
Line 594 ⟶ 621:
576
676
</pre>
=={{header|Haskell}}==
<syntaxhighlight lang="haskell">
module Squares
where
isPrime :: Int -> Bool
isPrime n
|n == 2 = True
|n == 1 = False
|otherwise = null $ filter (\i -> mod n i == 0 ) [2 .. root]
where
root :: Int
root = floor $ sqrt $ fromIntegral n
isSquare :: Int -> Bool
isSquare n = theFloor * theFloor == n
where
theFloor :: Int
theFloor = floor $ sqrt $ fromIntegral n
solution :: [Int]
solution = [d | d <- [1..999] , isSquare d && isPrime ( d + 1 )]
</syntaxhighlight>
{{out}}
<pre>
[1,4,16,36,100,196,256,400,576,676]
</pre>
Line 935 ⟶ 990:
END;
DECLARE (
TO$NEXT, I2 = 4; /* NOTE: ( 2N + 2 )^2 - 2N^2 = 8N + 4 */
DO WHILE I2 < 1000;
IF IS$PRIME( I2 + 1 ) THEN DO;
Line 945 ⟶ 999:
TO$NEXT = TO$NEXT + 8;
I2 = I2 + TO$NEXT;
END;
EOF
</syntaxhighlight>
{{out}}
<pre>
1 4 16 36 100 196 256 400 576 676
</pre>
=={{header|PROMAL}}==
{{Trans|ALGOL W}}
<syntaxhighlight lang="promal">
;;; Find squares n where n + 1 is prime
PROGRAM primesq
INCLUDE library
;;; returns TRUE(1) if p is prime, FALSE(0) otherwise
FUNC BYTE isPrime
ARG WORD n
WORD i
WORD f
WORD f2
WORD toNext
BYTE prime
BEGIN
IF n < 3
prime = n = 2
ELSE IF n % 3 = 0
prime = n = 3
ELSE IF n % 2 = 0
prime = 0
ELSE
prime = 1
f = 5
f2 = 25
toNext = 24 ; note: ( 2n + 1 )^2 - ( 2n - 1 )^2 = 8n
WHILE f2 <= n AND prime
prime = n % f <> 0
f = f + 2
f2 = toNext
toNext = toNext + 8
RETURN prime
END
WORD i2
WORD toNext
BEGIN
IF isPrime( ( 1 * 1 ) + 1 ) ; 1 is the only possible odd number
OUTPUT " 1"
i2 = 4
toNext = 4 ; note: ( 2n + 2 )^2 - 2n^2 = 8n + 4
WHILE i2 < 1000
IF isPrime( i2 + 1 )
OUTPUT " #W", i2
toNext = toNext + 8
i2 = i2 + toNext
END
</syntaxhighlight>
{{out}}
Line 985 ⟶ 1,094:
done...
</pre>
=={{header|Quackery}}==
<code>isprime</code> is defined at [[Primality by trial division#Quackery]].
<syntaxhighlight lang="Quackery"> [] [] 0
[ 1+ dup 2 **
dup 1000 < while
1+ isprime if
[ dup dip join ]
again ]
2drop
witheach [ 2 ** join ]
echo</syntaxhighlight>
{{out}}
<pre>[ 1 4 16 36 100 196 256 400 576 676 ]</pre>
=={{header|Racket}}==
Line 1,094 ⟶ 1,221:
{{out}}
<pre>
[1, 4, 16, 36, 100, 196, 256, 400, 576, 676]
</pre>
=={{header|Rust}}==
<syntaxhighlight lang="rust">
use primes::is_prime ;
fn is_square( number : u64 ) -> bool {
let floor : u64 = (number as f64).sqrt( ).floor( ) as u64 ;
floor * floor == number
}
fn main() {
let solution : Vec<u64> = (1..1000).into_iter( ).
filter( | d | is_square( *d ) && is_prime( *d + 1 )).collect( ) ;
println!("{:?}" , solution);
}
</syntaxhighlight>
{{out}}<pre>
[1, 4, 16, 36, 100, 196, 256, 400, 576, 676]
</pre>
Line 1,132 ⟶ 1,278:
576
676</pre>
=={{header|VTL-2}}==
{{Trans|TinyBASIC}}
<syntaxhighlight lang="vtl2">
1000 ?=1
1010 N=2
1020 M=4
1030 J=M+1
1040 #=2000
1050 #=P=1=0*1080
1060 $=32
1070 ?=M
1080 N=N+2
1090 M=N*N
1100 #=M<1000*1030
1110 #=9999
2000 R=!
2010 P=0
2020 I=3
2030 #=J/I*0+%=0*R
2040 I=I+2
2050 #=I*I<J*2030
2060 P=1
2070 #=R
</syntaxhighlight>
{{out}}
<pre>
1 4 16 36 100 196 256 400 576 676
</pre>
=={{header|Wren}}==
{{libheader|Wren-math}}
<syntaxhighlight lang="
var squares = []
| |||