Equal prime and composite sums: Difference between revisions

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<lang julia>using Primes

function getsequencematches(N)

function getsequencematches(N, masksize = 10_000_000_000)

pmask = primesmask(N)

pmask = primesmask(masksize)

psum, csum, pindex, cindex, pcount, ccount = 2, 4, 2, 4, 1, 1

found, psum, csum, pindex, cindex, pcount, ccount = 0, 2, 4, 2, 4, 1, 1

incrementpsum() = (pindex += 1; if pmask[pindex] psum += pindex; pcount += 1 end)

incrementcsum() = (cindex += 1; if !pmask[cindex] csum += cindex; ccount += 1 end)

while ~~pindex~~ < N

while found < N

while psum < csum

pindex >= N && return

pindex >= masksize && return

incrementpsum()

end

if psum == csum

println("Primes up to $pindex at position $pcount and composites up to $cindex at position $ccount sum to $psum.")

found += 1

while psum == csum

incrementpsum()

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end

getsequencematches(~~500_000_000~~)

@time getsequencematches(11)

</lang>{{out}}

<pre>

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Primes up to 86254457 at position 5012372 and composites up to 21123471 at position 19786181 sum to 209456854921713.

Primes up to 390180569 at position 20840220 and composites up to 91491160 at position 86192660 sum to 3950430820867201.

72.974740 seconds (1.09 G allocations: 19.829 GiB, 0.77% gc time)

</pre>