--- a/progs/pow.scala	Fri Sep 28 13:54:18 2018 +0100
+++ b/progs/pow.scala	Sun Sep 30 12:01:14 2018 +0100
@@ -1,5 +1,5 @@
 def concat(A: Set[String], B: Set[String]) : Set[String] =
-  for (x <-A ; y <- B) yield x ++ y
+  for (x <- A ; y <- B) yield x ++ y
 
 def pow(A: Set[String], n: Int) : Set[String] = n match {
   case 0 => Set("")
@@ -33,3 +33,7 @@
 
 val A = Set("a", "b", "")
 pow(A, 5).size   
+
+
+for (n <- (0 to 12).toList) 
+  yield pow(A, n).size
\ No newline at end of file