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Pairs with common factors: Difference between revisions

Added Go
(Added C)
(Added Go)
Line 323:
The 1,000,000th term: 196035947609</pre>
 
 
=={{header|Go}}==
{{trans|Wren}}
{{libheader|Go-rcu}}
<syntaxhighlight lang="go">package main
 
import (
"fmt"
"rcu"
)
 
func totient(n uint64) uint64 {
tot := n
i := uint64(2)
for i*i <= n {
if n%i == 0 {
for n%i == 0 {
n /= i
}
tot -= tot / i
}
if i == 2 {
i = 1
}
i += 2
}
if n > 1 {
tot -= tot / n
}
return tot
}
 
func ord(c int) string {
m := c % 100
if m >= 4 && m <= 20 {
return "th"
}
m %= 10
switch m {
case 1:
return "st"
case 2:
return "md"
case 3:
return "rd"
default:
return "th"
}
}
 
func main() {
const max = 1_000_000
a := make([]uint64, max)
sumPhi := uint64(0)
for n := uint64(1); n <= uint64(max); n++ {
sumPhi += totient(n)
if rcu.IsPrime(n) {
a[n-1] = a[n-2]
} else {
a[n-1] = n*(n-1)/2 + 1 - sumPhi
}
}
fmt.Println("Number of pairs with common factors - first one hundred terms:")
rcu.PrintTable(a[:100], 10, 6, true)
fmt.Println()
for limit := 1; limit <= max; limit *= 10 {
fmt.Printf("The %s%s term: %s\n", rcu.Commatize(limit), ord(limit), rcu.Commatize(a[limit-1]))
}
}</syntaxhighlight>
 
{{out}}
<pre>
Number of pairs with common factors - first one hundred terms:
0 0 0 1 1 4 4 7 9 14
14 21 21 28 34 41 41 52 52 63
71 82 82 97 101 114 122 137 137 158
158 173 185 202 212 235 235 254 268 291
291 320 320 343 363 386 386 417 423 452
470 497 497 532 546 577 597 626 626 669
669 700 726 757 773 818 818 853 877 922
922 969 969 1,006 1,040 1,079 1,095 1,148 1,148 1,195
1,221 1,262 1,262 1,321 1,341 1,384 1,414 1,461 1,461 1,526
1,544 1,591 1,623 1,670 1,692 1,755 1,755 1,810 1,848 1,907
 
The 1st term: 0
The 10th term: 14
The 100th term: 1,907
The 1,000th term: 195,309
The 10,000th term: 19,597,515
The 100,000th term: 1,960,299,247
The 1,000,000th term: 196,035,947,609
</pre>
 
=={{header|J}}==
9,485

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