Sequence: smallest number greater than previous term with exactly n divisors: Difference between revisions

From Rosetta Code
Content added Content deleted
(Clarified that 'factors' include unity and the number itself.)
(Added Go)
Line 6: Line 6:


Show the first 15 items of this sequence.
Show the first 15 items of this sequence.

=={{header|Go}}==
<lang go>package main

import "fmt"

func countDivisors(n int) int {
count := 0
for i := 1; i*i <= n; i++ {
if n%i == 0 {
if i == n/i {
count++
} else {
count += 2
}
}
}
return count
}

func main() {
const max = 15
fmt.Println("The first", max, "anti-primes plus are:")
for i, next := 1, 1; next <= max; i++ {
if next == countDivisors(i) {
fmt.Printf("%d ", i)
next++
}
}
fmt.Println()
}</lang>

{{out}}
<pre>
The first 15 anti-primes plus are:
1 2 4 6 16 18 64 66 100 112 1024 1035 4096 4288 4624
</pre>


=={{header|Ring}}==
=={{header|Ring}}==

Revision as of 08:13, 9 April 2019

Sequence: smallest number greater than previous term with exactly n divisors is a draft programming task. It is not yet considered ready to be promoted as a complete task, for reasons that should be found in its talk page.

The Anti-primes Plus sequence are the natural numbers in which each nth item has n factors, including 1 and itself.

Task

Show the first 15 items of this sequence.

Go

<lang go>package main

import "fmt"

func countDivisors(n int) int { 

   count := 0
   for i := 1; i*i <= n; i++ {
       if n%i == 0 {
           if i == n/i {
               count++
           } else {
               count += 2
           }
       }
   }
   return count

}

func main() { 

   const max = 15
   fmt.Println("The first", max, "anti-primes plus are:")
   for i, next := 1, 1; next <= max; i++ {
       if next == countDivisors(i) {
           fmt.Printf("%d ", i)
           next++
       }
   }
   fmt.Println()

}</lang>

Output:
The first 15 anti-primes plus are:
1 2 4 6 16 18 64 66 100 112 1024 1035 4096 4288 4624

Ring

<lang ring>

  1. Project : ANti-primes

see "working..." + nl see "wait for done..." + nl + nl see "the first 15 Anti-primes Plus are:" + nl + nl num = 1 n = 0 result = list(15) while num < 16 

     n = n + 1
     div = factors(n)
     if div = num
        result[num] = n
        num = num + 1
     ok

end see "[" for n = 1 to len(result) 

   if n < len(result)
      see string(result[n]) + ","
   else
      see string(result[n]) + "]" + nl + nl
   ok

next see "done..." + nl

func factors(an) 

    ansum = 2
    if an < 2
       return(1)
    ok
    for nr = 2 to an/2
        if an%nr = 0
           ansum = ansum+1
        ok
    next
    return ansum

</lang>

Output:
working...
wait for done...

the first 15 Anti-primes Plus are:

[1,2,4,6,16,18,64,66,100,112,1024,1035,4096,4288,4624]

done...
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