use Data::Dumper;
my $set_group_size = 2;
my @list = 1..5;
print Dumper ([ sumList($set_group_size,@list) ]);

sub sumList {
	my @sumlist;
	my $size = shift;	
	while ( @_ ) {
		my @current = splice @_, 0, $size-1;
		foreach my $item (@_) {
			push ( @sumlist, [@current,$item] );
		}
		unshift (@_, @current[1..$#current]);
	}
	return @sumlist;
}