diff -r 0a42d73e795b -r 4b454a6d1814 progs/collatz.scala
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/progs/collatz.scala	Sun Aug 21 00:37:27 2016 +0100
@@ -0,0 +1,5 @@
+def collatz(n: BigInt) : Boolean = {
+  if (n == 1) true else 
+  if (n % 2 == 0) collatz(n / 2) else 
+  collatz(3 * n + 1)
+}