Multiplicatively perfect numbers: Difference between revisions

Line 800:

This includes '1' as an MPN.

This includes '1' as an MPN. Not very quick at around 112 seconds but reasonable for Wren.

<syntaxhighlight lang="ecmascript">import "./math" for Int, Nums

import "./fmt" for Fmt

// library method customized for this task

var divisors = Fn.new { |n|

var divisors = []

var i = 1

var k = (n%2 == 0) ? 1 : 2

while (i <= n.sqrt) {

if (i > 1 && n%i == 0) { // exclude 1 and n

divisors.add(i)

if (divisors.count > 2) break // not eligible if has > 2 divisors

var j = (n/i).floor

if (j != i) divisors.add(j)

}

i = i + k

}

return divisors

}

var limit = 500

var count = 0

var i = 0

var i = 1

System.print("Multiplicatively perfect numbers under %(limit):")

while (true) {

var pd = (i != 1) ? ~~Int~~.~~properDivisors~~(i~~).skip(1~~) : [1, 1]

var pd = (i != 1) ? divisors.call(i) : [1, 1]

if (pd.count > 1 && ~~Nums.prod(~~pd) == i) {

if (pd.count == 2 && pd[0] * pd[1] == i) {

count = count + 1

if (i < 500) {

var pds = ~~pd.map { |d|~~ Fmt.d(3, d) ~~}.join(~~" x ")

var pds = Fmt.swrite("$3d x $3d", pd[0], pd[1])

Fmt.write("$3d = $s ", i, pds)

if (count % 5 == 0) System.print()

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Line 840:

var cubes = Int.primeCount((limit - 1).cbrt.floor)

var count2 = count + squares - cubes - 1

Fmt.print("Counts under $,7d: MPNs = $,7d Semi-primes = $,7d", limit, count, count2)

Fmt.print("Counts under $,9d: MPNs = $,7d Semi-primes = $,7d", limit, count, count2)

if (limit == ~~500000~~) return

if (limit == 5000000) return

limit = limit * 10

}

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482 = 2 x 241 485 = 5 x 97 489 = 3 x 163 493 = 17 x 29 497 = 7 x 71

Counts under 500: MPNs = 150 Semi-primes = 153

Counts under 5,000: MPNs = 1,354 Semi-primes = 1,365

Counts under 50,000: MPNs = 12,074 Semi-primes = 12,110

Counts under 500,000: MPNs = 108,223 Semi-primes = 108,326

Counts under 5,000,000: MPNs = 978,983 Semi-primes = 979,274

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