Sequence: smallest number with exactly n divisors
Sequence: smallest number 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.
Calculate the sequence where each term an is the smallest natural number that has exactly n divisors.
- Task
Show here, on this page, at least the first 15 terms of the sequence.
- See also
- Related tasks
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 seq := make([]int, max) fmt.Println("The first", max, "terms of the sequence are:") for i, n := 1, 0; n < max; i++ { if k := countDivisors(i); k <= max && seq[k-1] == 0 { seq[k-1] = i n++ } } fmt.Println(seq)
}</lang>
- Output:
The first 15 terms of the sequence are: [1 2 4 6 16 12 64 24 36 48 1024 60 4096 192 144]
Perl
<lang perl>use strict; use warnings; use ntheory 'divisors';
print "First 15 terms of OEIS: A005179\n"; for my $n (1..15) {
my $l = 0; while (++$l) { print "$l " and last if $n == divisors($l); }
}</lang>
- Output:
First 15 terms of OEIS: A005179 1 2 4 6 16 12 64 24 36 48 1024 60 4096 192 144
REXX
<lang rexx></lang>
Perl 6
<lang perl6>sub div-count (\x) {
return 2 if x.is-prime; +flat (1 .. x.sqrt.floor).map: -> \d { unless x % d { my \y = x div d; y == d ?? y !! (y, d) } }
}
my $limit = 15;
put "First $limit terms of OEIS:A005179"; put (1..$limit).map: -> $n { first { $n == .&div-count }, 1..Inf };
</lang>
- Output:
First 15 terms of OEIS:A005179 1 2 4 6 16 12 64 24 36 48 1024 60 4096 192 144