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- #!/usr/bin/perl
- # Daniel "Trizen" Șuteu
- # Date: 25 July 2021
- # https://github.com/trizen
- # Sum of Euler phi function phi(k) for 2 <= k <= 10^6.
- # https://projecteuler.net/problem=72
- # Runtime: 0.119s
- use 5.020;
- use strict;
- use warnings;
- use ntheory qw(moebius mertens);
- use Math::AnyNum qw(dirichlet_sum);
- #use Math::Sidef qw(:all);
- use experimental qw(signatures);
- say dirichlet_sum(1e6, sub ($n) { moebius($n) }, sub ($n) { $n },
- sub ($n) { mertens($n) }, sub ($n) { ($n*($n+1))>>1 })-1;
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