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#!/usr/bin/perl
use warnings;
use strict;
use feature qw{ say };
use List::Util qw{ sum };
my @primes = (2, 3, 5);
sub prime_factors {
my ($n) = @_;
my $p = $primes[-1] + 2;
while ($p < 1 + $n / 2) {
push @primes, $p unless grep 0 == $p % $_, @primes;
$p += 2;
}
my $m = $n;
my @factors;
for my $p (@primes) {
if (0 == $m % $p) {
$m /= $p;
push @factors, $p;
redo
}
}
return @factors
}
sub smith_numbers {
my ($count) = @_;
my @smith;
my $n = 4;
while (@smith < $count) {
my @factors = prime_factors($n);
next unless @factors > 1;
push @smith, $n
if sum(split //, join "", @factors) == sum(split //, $n);
} continue {
++$n;
}
return @smith
}
use Test2::V0;
plan 1;
is [smith_numbers(10)], [4, 22, 27, 58, 85, 94, 121, 166, 202, 265];
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