Smallest number k such that k+2^m is composite for all m less than k: Difference between revisions
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<pre> |
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773 2131 2491 4471 5101 |
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=={{header|Java}}== |
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<syntaxhighlight lang="java"> |
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import java.math.BigInteger; |
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public final class SmallestNumberK { |
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public static void main(String[] aArgs) { |
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int count = 0; |
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int k = 3; |
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while ( count < 5 ) { |
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if ( isValid(k) ) { |
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System.out.print(k + " "); |
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count += 1; |
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} |
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k += 2; |
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} |
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System.out.println(); |
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} |
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private static boolean isValid(int aK) { |
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final BigInteger bigK = BigInteger.valueOf(aK); |
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for ( int m = 1; m < aK; m++ ) { |
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if ( bigK.add(BigInteger.ONE.shiftLeft(m)).isProbablePrime(20) ) { |
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return false; |
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} |
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} |
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return true; |
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} |
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} |
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</syntaxhighlight> |
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<pre> |
<pre> |
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773 2131 2491 4471 5101 |
773 2131 2491 4471 5101 |
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