Data commit

Task/Emirp-primes/Sidef/emirp-primes.sidef

@@ -0,0 +1,31 @@
+func forprimes(a, b, callback) {
+    for (var p = a.dec.next_prime; p <= b; p.next_prime!) {
+        callback(p)
+    }
+}
+
+func is_emirp(p) {
+    var str = Str(p)
+    var rev = str.reverse
+    (str != rev) && is_prime(Num(rev))
+}
+
+func emirp_list(count) {
+    var i = 13
+    var inc = (100 + 10*count)
+    var n = []
+    while (n.len < count) {
+        forprimes(i, i+inc - 1, {|p|
+            is_emirp(p) && (n << p)
+        })
+        (i, inc) = (i+inc, int(inc * 1.03) + 1000)
+    }
+    n.splice(count)
+    return n
+}
+
+say ("First 20: ", emirp_list(20).join(' '))
+say ("Between 7700 and 8000: ", gather {
+        forprimes(7700, 8000, {|p| is_emirp(p) && take(p) })
+    }.join(' '))
+say ("The 10,000'th emirp: ", emirp_list(10000)[-1])