Sum of primes in odd positions is prime: Difference between revisions
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m (added to Prime Numbers category.) |
Catskill549 (talk | contribs) (added AWK) |
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119 653 17959 |
119 653 17959 |
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143 823 26879 |
143 823 26879 |
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</pre> |
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=={{header|AWK}}== |
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<lang AWK> |
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# syntax: GAWK -f SUM_OF_PRIMES_IN_ODD_POSITIONS_IS_PRIME.AWK |
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# converted from Ring |
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BEGIN { |
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print(" i p sum") |
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print("------ ------ ------") |
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start = 2 |
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stop = 999 |
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for (i=start; i<=stop; i++) { |
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if (is_prime(i)) { |
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if (++nr % 2 == 1) { |
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sum += i |
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if (is_prime(sum)) { |
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count++ |
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printf("%6d %6d %6d\n",nr,i,sum) |
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} |
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} |
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} |
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} |
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printf("Odd indexed primes %d-%d: %d\n",start,stop,count) |
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exit(0) |
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} |
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function is_prime(x, i) { |
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if (x <= 1) { |
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return(0) |
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} |
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for (i=2; i<=int(sqrt(x)); i++) { |
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if (x % i == 0) { |
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return(0) |
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} |
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} |
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return(1) |
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} |
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</lang> |
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{{out}} |
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<pre> |
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i p sum |
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------ ------ ------ |
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1 2 2 |
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3 5 7 |
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11 31 89 |
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27 103 659 |
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35 149 1181 |
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67 331 5021 |
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91 467 9923 |
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95 499 10909 |
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99 523 11941 |
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119 653 17959 |
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143 823 26879 |
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Odd indexed primes 2-999: 11 |
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</pre> |
</pre> |
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