Numbers whose count of divisors is prime: Difference between revisions
Numbers whose count of divisors is prime (view source)
Revision as of 21:13, 2 November 2021
, 2 years agoadded AWK
m (Peak moved page Numbers which count of divisors is prime to Numbers whose count of divisors is prime: "which" is ungrammatical here, "whose" is acceptable and yields a similar title.) |
Catskill549 (talk | contribs) (added AWK) |
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52441 54289 57121 58081 59049 63001 65536 66049 69169 72361
73441 76729 78961 80089 83521 85849 94249 96721 97969
</pre>
=={{header|AWK}}==
<lang AWK>
# syntax: GAWK -f NUMBERS_WHOSE_COUNT_OF_DIVISORS_IS_PRIME.AWK
BEGIN {
start = 2
stop = 99999
stop2 = 999
for (i=start; i*i<=stop; i++) {
n = count_divisors(i*i)
if (n>2 && is_prime(n)) {
printf("%6d%1s",i*i,++count%10?"":"\n")
if (i*i <= stop2) {
count2++
}
}
}
printf("\nNumbers with odd prime divisor counts %d-%d: %d\n",start,stop2,count2)
printf("Numbers with odd prime divisor counts %d-%d: %d\n",start,stop,count)
exit(0)
}
function count_divisors(n, count,i) {
for (i=1; i*i<=n; i++) {
if (n % i == 0) {
count += (i == n / i) ? 1 : 2
}
}
return(count)
}
function is_prime(x, i) {
if (x <= 1) {
return(0)
}
for (i=2; i<=int(sqrt(x)); i++) {
if (x % i == 0) {
return(0)
}
}
return(1)
}
</lang>
{{out}}
<pre>
4 9 16 25 49 64 81 121 169 289
361 529 625 729 841 961 1024 1369 1681 1849
2209 2401 2809 3481 3721 4096 4489 5041 5329 6241
6889 7921 9409 10201 10609 11449 11881 12769 14641 15625
16129 17161 18769 19321 22201 22801 24649 26569 27889 28561
29929 32041 32761 36481 37249 38809 39601 44521 49729 51529
52441 54289 57121 58081 59049 63001 65536 66049 69169 72361
73441 76729 78961 80089 83521 85849 94249 96721 97969
Numbers with odd prime divisor counts 2-999: 16
Numbers with odd prime divisor counts 2-99999: 79
</pre>
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