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- #!/usr/bin/julia
- # Daniel "Trizen" Șuteu
- # License: GPLv3
- # Date: 29 September 2016
- # Website: https://github.com/trizen
- # https://projecteuler.net/problem=512
- # Runtime: ~20 min
- using Primes
- @inline function eulerphi(n::Int64)
- for p in keys(factor(n))
- n -= div(n, p)
- end
- n
- end
- function g(n::Int64)
- sum = 0
- for k in 0:div(n, 2)-1
- sum += eulerphi(2*k + 1)
- end
- sum
- end
- println(g(5 * 10^8))
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