Extra primes: Difference between revisions

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 </pre>
+=={{header|Kotlin}}==
+{{trans|Java}}
+<lang scala>private fun nextPrimeDigitNumber(n: Int): Int {
+    return if (n == 0) {
+    } else when (n % 10) {
+-> n + 1
+, 5 -> n + 2
+        else -> 2 + nextPrimeDigitNumber(n / 10) * 10
+    }
+}
+private fun isPrime(n: Int): Boolean {
+    if (n < 2) {
+        return false
+    }
+    if (n and 1 == 0) {
+        return n == 2
+    }
+    if (n % 3 == 0) {
+        return n == 3
+    }
+    if (n % 5 == 0) {
+        return n == 5
+    }
+    val wheel = intArrayOf(4, 2, 4, 2, 4, 6, 2, 6)
+    var p = 7
+    while (true) {
+        for (w in wheel) {
+            if (p * p > n) {
+                return true
+            }
+            if (n % p == 0) {
+                return false
+            }
+            p += w
+        }
+    }
+}
+private fun digitSum(n: Int): Int {
+    var nn = n
+    var sum = 0
+    while (nn > 0) {
+        sum += nn % 10
+        nn /= 10
+    }
+    return sum
+}
+fun main() {
+    val limit = 10000
+    var p = 0
+    var n = 0
+    println("Extra primes under $limit:")
+    while (p < limit) {
+        p = nextPrimeDigitNumber(p)
+        if (isPrime(p) && isPrime(digitSum(p))) {
+            n++
+            println("%2d: %d".format(n, p))
+        }
+    }
+    println()
+}</lang>
+{{out}}
+<pre>Extra primes under 10000:
+: 2
+: 3
+: 5
+: 7
+: 23
+: 223
+: 227
+: 337
+: 353
+: 373
+: 557
+: 577
+: 733
+: 757
+: 773
+: 2333
+: 2357
+: 2377
+: 2557
+: 2753
+: 2777
+: 3253
+: 3257
+: 3323
+: 3527
+: 3727
+: 5233
+: 5237
+: 5273
+: 5323
+: 5527
+: 7237
+: 7253
+: 7523
+: 7723
+: 7727</pre>
 =={{header|MAD}}==