Perfect numbers: Difference between revisions

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 ===Version 2===
+{{libheader|Wren-math}}
 This makes use of the fact that all known perfect numbers are of the form <big> (2<sup>''n''</sup> - 1) × 2<sup>''n'' - 1</sup></big> where <big> (2<sup>''n''</sup> - 1)</big> is prime and finds the first seven perfect numbers instantly. The numbers are too big after that to be represented accurately by Wren.
-<lang ecmascript>var isPrime = Fn.new { |n|
+<lang ecmascript>import "/math" for Int
-    if (n < 2 || !n.isInteger) return false
-    if (n%2 == 0) return n == 2
-    if (n%3 == 0) return n == 3
-    var d = 5
-    while (d*d <= n) {
-        if (n%d == 0) return false
-        d = d + 2
-        if (n%d == 0) return false
-        d = d + 4
-    }
-    return true
-}
 var isPerfect = Fn.new { |n|
@@ Line 3,276: / Line 3,265: @@
 while (count < 7) {
     var n = 2.pow(p) - 1
-    if (isPrime.call(n)) {
+    if (Int.isPrime(n)) {
         n = n * 2.pow(p-1)
         if (isPerfect.call(n)) {