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Perfect numbers: Difference between revisions

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Perfect numbers (view source)

Revision as of 14:53, 29 May 2020

256 bytes removed ,  4 years ago
→‎Version 2: Now uses Wren-math module.
m (Phix/mpfr)
(→‎Version 2: Now uses Wren-math module.)
Line 3,243:
 
===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>varimport isPrime"/math" =for Fn.new { |n|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 ⟶ 3,265:
while (count < 7) {
var n = 2.pow(p) - 1
if (isPrimeInt.callisPrime(n)) {
n = n * 2.pow(p-1)
if (isPerfect.call(n)) {
PureFox
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