Sequence: nth number with exactly n divisors: Difference between revisions
Sequence: nth number with exactly n divisors (view source)
Revision as of 10:27, 14 June 2019
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33 : 12166144
</pre>
=={{header|Julia}}==
<lang julia>using Primes
function countdivisors(n)
f = [one(n)]
for (p, e) in factor(n)
f = reduce(vcat, [f * p ^ j for j in 1:e], init = f)
end
length(f)
end
function nthwithndivisors(N)
parray = findall(primesmask(100 * N))
for i = 1:N
if isprime(i)
println("$i : ", BigInt(parray[i])^(i-1))
else
k = 0
for j in 1:100000000000
if isodd(i) && Int(floor(sqrt(j)))^2 != j
continue
elseif i == countdivisors(j) && (k += 1) == i
println("$i : $j")
break
end
end
end
end
end
nthwithndivisors(35)
</lang>{{out}}
<pre>
1 : 1
2 : 3
3 : 25
4 : 14
5 : 14641
6 : 44
7 : 24137569
8 : 70
9 : 1089
10 : 405
11 : 819628286980801
12 : 160
13 : 22563490300366186081
14 : 2752
15 : 9801
16 : 462
17 : 21559177407076402401757871041
18 : 1044
19 : 740195513856780056217081017732809
20 : 1520
21 : 141376
22 : 84992
23 : 1658509762573818415340429240403156732495289
24 : 1170
25 : 52200625
26 : 421888
27 : 52900
28 : 9152
29 : 1116713952456127112240969687448211536647543601817400964721
30 : 6768
31 : 1300503809464370725741704158412711229899345159119325157292552449
32 : 3990
33 : 12166144
34 : 9764864
35 : 446265625
</pre>
=={{header|Kotlin}}==
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