if you want to print the contents of an array just do:

my @array = (1,2,3);
print join(',', @array);
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in the code you posted try replacing

print "@$_\n", [ @$included, $nextValue ]
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with print join(", ", @{[ @$included, $nextValue ]})."\n"

Edit:btw, your code does not return anything in @results. Instead of printing inside your sub, try pushing each new result to the @results array by replacing said print statement with push(@results, [ @$included, $nextValue ]). Then at the end of your code (after Solve() returns) do  print join(",", @$_)."\n" foreach @results

I was wondering what @$_ in print "@$_\n", [ @$included, $nextValue ] was all about...