Data commit

Task/Van-Eck-sequence/Jq/van-eck-sequence-1.jq

@@ -0,0 +1,19 @@
+# Input: an array
+# If the rightmost element, .[-1], does not occur elsewhere, return 0;
+# otherwise return the "depth" of its rightmost occurrence in .[0:-2]
+def depth:
+  .[-1] as $x
+  | length as $length
+  | first(range($length-2; -1; -1) as $i
+          | select(.[$i] == $x) | $length - 1 - $i)
+     // 0 ;
+
+# Generate a stream of the first $n van Eck integers:
+def vanEck($n):
+  def v:
+    recurse( if length == $n then empty
+             else . + [depth] end );
+  [0] | v | .[-1];
+
+# The task:
+[vanEck(10)], [vanEck(1000)][990:1001]

Task/Van-Eck-sequence/Jq/van-eck-sequence-2.jq

@@ -0,0 +1,2 @@
+[0,0,1,0,2,0,2,2,1,6]
+[4,7,30,25,67,225,488,0,10,136]