6 files changed, 109 insertions, 0 deletions
diff --git a/challenge-175/arne-sommer/blog.txt b/challenge-175/arne-sommer/blog.txt
new file mode 100644
index 0000000000..377d59fa68
--- /dev/null
+++ b/challenge-175/arne-sommer/blog.txt
@@ -0,0 +1 @@
+https://raku-musings.com/perfect-at-last.html
diff --git a/challenge-175/arne-sommer/raku/ch-1.raku b/challenge-175/arne-sommer/raku/ch-1.raku
new file mode 100755
index 0000000000..20a2813fee
--- /dev/null
+++ b/challenge-175/arne-sommer/raku/ch-1.raku
@@ -0,0 +1,12 @@
+#! /usr/bin/env raku
+
+unit sub MAIN (Int $year = Date.today.year);
+
+for 1 .. 12 -> $month
+{
+  my $date = Date.new($year, $month, Date.new($year, $month, 1).days-in-month);
+
+  $date.=pred while $date.day-of-week != 7;
+
+  say $date;
+}
diff --git a/challenge-175/arne-sommer/raku/ch-2.raku b/challenge-175/arne-sommer/raku/ch-2.raku
new file mode 100755
index 0000000000..4a34211631
--- /dev/null
+++ b/challenge-175/arne-sommer/raku/ch-2.raku
@@ -0,0 +1,36 @@
+#! /usr/bin/env raku
+
+unit sub MAIN (Int $count where $count > 0 = 20, :v(:$verbose));
+
+my $ptm := (1 .. Inf).grep( *.&is-ptm );
+
+say $ptm[^$count].join(", ");
+
+sub is-ptm ($number)
+{
+  my @totients;
+  my $c = $number;
+
+  while $c > 1
+  {
+    $c = totient($c);
+    @totients.push: $c;
+  }
+
+say ":: $number [@totients[]] sum:{ @totients.sum } { $number == @totients.sum ?? "match" !! "" }" if $verbose;
+
+  return @totients.sum == $number;
+}
+
+sub totient ($number)
+{
+  my $count = 0;
+
+  for 1 .. $number -1 -> $candidate
+  {
+    $count++ if $number gcd $candidate == 1;
+  }
+
+  return $count;
+}
+
diff --git a/challenge-175/arne-sommer/raku/last-sunday b/challenge-175/arne-sommer/raku/last-sunday
new file mode 100755
index 0000000000..20a2813fee
--- /dev/null
+++ b/challenge-175/arne-sommer/raku/last-sunday
@@ -0,0 +1,12 @@
+#! /usr/bin/env raku
+
+unit sub MAIN (Int $year = Date.today.year);
+
+for 1 .. 12 -> $month
+{
+  my $date = Date.new($year, $month, Date.new($year, $month, 1).days-in-month);
+
+  $date.=pred while $date.day-of-week != 7;
+
+  say $date;
+}
diff --git a/challenge-175/arne-sommer/raku/last-sunday-oneliner b/challenge-175/arne-sommer/raku/last-sunday-oneliner
new file mode 100755
index 0000000000..5f1443ea22
--- /dev/null
+++ b/challenge-175/arne-sommer/raku/last-sunday-oneliner
@@ -0,0 +1,12 @@
+#! /usr/bin/env raku
+
+-> $year
+{
+  -> $month
+  {
+    -> $date
+    {
+      say $date.earlier(days => $date.day-of-week == 7 ?? ( 0 ) !! ( $date.day-of-week ) )
+    }(Date.new($year, $month, Date.new($year, $month, 1).days-in-month))
+  }($_) for 1 .. 12
+}(@*ARGS[0] // Date.today.year);
diff --git a/challenge-175/arne-sommer/raku/ptm b/challenge-175/arne-sommer/raku/ptm
new file mode 100755
index 0000000000..4a34211631
--- /dev/null
+++ b/challenge-175/arne-sommer/raku/ptm
@@ -0,0 +1,36 @@
+#! /usr/bin/env raku
+
+unit sub MAIN (Int $count where $count > 0 = 20, :v(:$verbose));
+
+my $ptm := (1 .. Inf).grep( *.&is-ptm );
+
+say $ptm[^$count].join(", ");
+
+sub is-ptm ($number)
+{
+  my @totients;
+  my $c = $number;
+
+  while $c > 1
+  {
+    $c = totient($c);
+    @totients.push: $c;
+  }
+
+say ":: $number [@totients[]] sum:{ @totients.sum } { $number == @totients.sum ?? "match" !! "" }" if $verbose;
+
+  return @totients.sum == $number;
+}
+
+sub totient ($number)
+{
+  my $count = 0;
+
+  for 1 .. $number -1 -> $candidate
+  {
+    $count++ if $number gcd $candidate == 1;
+  }
+
+  return $count;
+}
+