Check if sum of first n primes is prime: Difference between revisions
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{{Draft task}} |
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;Task:Check if sum of first '''n''' primes is prime, where '''n <= 158''' |
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<br><br> |
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=={{header|Julia}}== |
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<lang julia>using Primes |
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</lang> |
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The sum of the first 20 primes is |
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<lang julia>julia> sum(prime(i) for i in 1:20) |
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639 |
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</lang> |
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So, with a bit of experimentation, we find that to duplicate the Ring result we need to sum up to the first 158 primes, which then |
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gives us 20 prime results when we filter for a prime number as the sum: |
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<lang julia>julia> filter(p -> isprime(last(p)), accumulate(+, primes(prime(158))) |> enumerate |> collect) |
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20-element Vector{Tuple{Int64, Int64}}: |
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(1, 2) |
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(2, 5) |
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(4, 17) |
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(6, 41) |
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(12, 197) |
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(14, 281) |
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(60, 7699) |
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(64, 8893) |
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(96, 22039) |
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(100, 24133) |
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(102, 25237) |
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(108, 28697) |
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(114, 32353) |
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(122, 37561) |
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(124, 38921) |
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(130, 43201) |
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(132, 44683) |
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(146, 55837) |
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(152, 61027) |
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(158, 66463) |
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</lang> |
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=={{header|Ring}}== |
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<lang ring> |
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load "stdlib.ring" |
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see "working..." + nl |
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see "Sum of first primes is prime:" + nl |
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n = 0 |
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nr = 0 |
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num = 0 |
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primSum = 0 |
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while true |
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n++ |
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if isprime(n) |
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nr++ |
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primSum += n |
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if isprime(primSum) |
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num++ |
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see "n" + "(" + nr + ") = " + primsum + " is prime" + nl |
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ok |
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ok |
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if num = 20 |
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exit |
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ok |
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end |
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see "done..." + nl |
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</lang> |
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{{out}} |
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<pre> |
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working... |
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Sum of first primes is prime: |
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n(1) = 2 is prime |
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n(2) = 5 is prime |
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n(4) = 17 is prime |
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n(6) = 41 is prime |
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n(12) = 197 is prime |
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n(14) = 281 is prime |
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n(60) = 7699 is prime |
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n(64) = 8893 is prime |
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n(96) = 22039 is prime |
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n(100) = 24133 is prime |
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n(102) = 25237 is prime |
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n(108) = 28697 is prime |
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n(114) = 32353 is prime |
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n(122) = 37561 is prime |
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n(124) = 38921 is prime |
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n(130) = 43201 is prime |
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n(132) = 44683 is prime |
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n(146) = 55837 is prime |
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n(152) = 61027 is prime |
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n(158) = 66463 is prime |
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done... |
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</pre> |
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