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- #!/usr/bin/perl
- # Daniel "Trizen" Șuteu
- # License: GPLv3
- # Date: 28 September 2016
- # Website: https://github.com/trizen
- # https://projecteuler.net/problem=512
- # Runtime: 5 min 02.77s
- use 5.010;
- use strict;
- use integer;
- use ntheory qw(euler_phi);
- sub g {
- my ($n) = @_;
- my $sum = 0;
- for (my $k = 1 ; $k <= $n ; $k += 2) {
- $sum += euler_phi($k);
- }
- $sum;
- }
- say g(5 * 10**8);
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