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Task/Ludic-numbers/Sidef/ludic-numbers.sidef

@@ -0,0 +1,24 @@
+func ludics_upto(nmax=100000) {
+  Enumerator({ |collect|
+    collect(1)
+    var arr = @(2..nmax)
+    while (arr) {
+      collect(var n = arr[0])
+      arr.range.by(n).each {|i| arr[i] = nil}
+      arr.compact!
+    }
+  })
+}
+
+func ludics_first(n) {
+    ludics_upto(n * n.log2).first(n)
+}
+
+say("First 25 Ludic numbers: ",     ludics_first(25).join(' '))
+say("Ludics below 1000: ",          ludics_upto(1000).len)
+say("Ludic numbers 2000 to 2005: ", ludics_first(2005).last(6).join(' '))
+
+var a = ludics_upto(250).to_a
+say("Ludic triples below 250: ", a.grep{|x| a.contains_all([x+2, x+6]) } \
+                                  .map {|x| '(' + [x, x+2, x+6].join(' ') + ')' } \
+                                  .join(' '))