1 files changed, 25 insertions, 0 deletions
diff --git a/023.pl b/023.pl
new file mode 100755
index 0000000..c145fb7
--- /dev/null
+++ b/023.pl
@@ -0,0 +1,25 @@
+#!/usr/bin/perl
+use strict;
+use warnings;
+use Math::Factor::XS qw/factors/;
+use List::Util qw/sum/;
+
+sub abundant {
+    my ($n) = @_;
+    return 1 + (sum(factors($n)) || 0) > $n;
+}
+
+my @abundant = grep { abundant($_) } 1..28123;
+my %sums;
+A: for my $a (@abundant) {
+    for my $b (@abundant) {
+        my $n = $a + $b;
+        next A if $n > 28123;
+        $sums{$n} = 1;
+    }
+}
+my $total = 0;
+for my $n (1..28123) {
+    $total += $n unless exists $sums{$n};
+}
+print "$total\n";