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diff --git a/challenge-143/wlmb/perl/ch-2.pl b/challenge-143/wlmb/perl/ch-2.pl
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+++ b/challenge-143/wlmb/perl/ch-2.pl
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+#!/usr/bin/env perl
+# Perl weekly challenge 143
+# Task 1: Stealthy number
+#
+# See https://wlmb.github.io/2021/12/13/PWC143/#task-2-stealthy-number
+use v5.12;
+use warnings;
+use PDL;
+use PDL::NiceSlice;
+foreach my $N(@ARGV){
+    my $Q=sqrt($N); # largest possible small divisor
+    my $s=(sequence($Q)+1);
+    my $d=$s->where($N % $s == 0); # list of divisors<=$Q
+    my $c=$d->cat($d(*)); # cartesian product of divisors
+    my $mask=$d+$N/$d==($d+$N/$d+1)->(*);
+    # Get pairs of divisors that obey the stealthy condition
+    my $d2=$c->whereND(($d+$N/$d)==($d+$N/$d+1)->(*));
+    my $out=$d2->nelem?1:0;
+    say "\nInput: $N Output: ", $out;
+    say "since ", $_((0)),"+",$N/$_((0)),
+        "==",$_((1)),"+",$N/$_((1)),"+1"
+        foreach $d2->transpose->dog;
+}