Palindromic primes in base 16
- Task
- Find palindromic primes in base 16, where n < 500
Factor
<lang factor>USING: kernel math.parser math.primes prettyprint sequences sequences.extras ;
500 primes-upto [ >hex ] [ dup reverse = ] map-filter .</lang>
- Output:
V{ "2" "3" "5" "7" "b" "d" "11" "101" "151" "161" "191" "1b1" "1c1" }
Go
<lang go>package main
import (
"fmt" "rcu" "strconv" "strings"
)
func reverse(s string) string {
chars := []rune(s) for i, j := 0, len(chars)-1; i < j; i, j = i+1, j-1 { chars[i], chars[j] = chars[j], chars[i] } return string(chars)
}
func main() {
fmt.Println("Primes < 500 which are palindromic in base 16:") primes := rcu.Primes(500) count := 0 for _, p := range primes { hp := strconv.FormatInt(int64(p), 16) if hp == reverse(hp) { fmt.Printf("%3s ", strings.ToUpper(hp)) count++ if count%5 == 0 { fmt.Println() } } } fmt.Println("\n\nFound", count, "such primes.")
}</lang>
- Output:
Primes < 500 which are palindromic in base 16: 2 3 5 7 B D 11 101 151 161 191 1B1 1C1 Found 13 such primes.
Ring
<lang ring> load "stdlib.ring" see "working..." + nl see "Palindromic primes in base 16:" + nl row = 0 decList = 0:15 baseList = ["0","1","2","3","4","5","6","7","8","9","A","B","C","D","E","F"] limit = 500
for n = 1 to limit
hex = hex(n) if ispalindrome(hex) and isprime(n) see "" + upper(hex) + " " row = row + 1 if row%5 = 0 see nl ok ok
next
see nl + "Found " + row + " palindromic primes in base 16" + nl see "done..." + nl </lang>
- Output:
working... Palindromic primes in base 16: 2 3 5 7 B D 11 101 151 161 191 1B1 1C1 Found 13 palindromic primes in base 16 done...
Wren
<lang ecmascript>import "/math" for Int import "/fmt" for Conv, Fmt
System.print("Primes < 500 which are palindromic in base 16:") var primes = Int.primeSieve(500) var count = 0 for (p in primes) {
var hp = Conv.Itoa(p, 16) if (hp == hp[-1..0]) { Fmt.write("$3s ", hp) count = count + 1 if (count % 5 == 0) System.print() }
} System.print("\n\nFound %(count) such primes.")</lang>
- Output:
Primes < 500 which are palindromic in base 16: 2 3 5 7 B D 11 101 151 161 191 1B1 1C1 Found 13 such primes.