15 lines
451 B
Text
15 lines
451 B
Text
/* Function to count the number of pairs below n */
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twin_primes_under_n(n):=block(
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L:makelist([6*i-1,6*i+1],i,1,floor(n/6)),
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caching:length(L),
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L1:[],
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for i from 1 thru caching do if map(primep,L[i])=[true,true] then push(L[i],L1),
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append([[3,5]],reverse(L1)),
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length(%%));
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/* Test cases */
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twin_primes_under_n(10);
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twin_primes_under_n(100);
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twin_primes_under_n(1000);
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twin_primes_under_n(10000);
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twin_primes_under_n(100000);
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