Double Twin Primes: Difference between revisions
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→{{header|ALGOL 68}}: Tweak |
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[]BOOL prime = PRIMESIEVE 1 000; |
[]BOOL prime = PRIMESIEVE 1 000; |
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INT count := 0; |
INT count := 0; |
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INT p := 3; # 2 cannot be a twin prime, so start with 3 # |
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WHILE p <= UPB prime - 8 DO |
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BOOL is double twin := FALSE; |
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IF prime[ p ] THEN |
IF prime[ p ] THEN |
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IF prime[ p + 2 ] THEN |
IF prime[ p + 2 ] THEN |
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IF prime[ p + 6 ] THEN |
IF prime[ p + 6 ] THEN |
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IF prime[ p + 8 ] THEN |
IF prime[ p + 8 ] THEN |
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count +:= 1; |
count +:= 1; |
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is double twin := TRUE; |
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print( ( "[" |
print( ( "[" |
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, whole( p, -4 ), whole( p + 2, -4 ) |
, whole( p, -4 ), whole( p + 2, -4 ) |
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FI |
FI |
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FI |
FI |
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FI |
FI; |
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p +:= IF is double twin THEN 6 ELSE 2 FI |
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OD; |
OD; |
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print( ( "Found ", whole( count, 0 ), " double twin primes below ", whole( UPB prime, 0 ), newline ) ) |
print( ( "Found ", whole( count, 0 ), " double twin primes below ", whole( UPB prime, 0 ), newline ) ) |