Summarize primes: Difference between revisions
→{{header|Scala}}
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</pre>
=={{header|Scala}}==
<syntaxhighlight lang="scala">object PrimeSum extends App {
</syntaxhighlight>▼
val oddPrimes: LazyList[Int] = 3 #:: LazyList.from(5, 2)
.filter(p => oddPrimes.takeWhile(_ <= math.sqrt(p)).forall(p % _ > 0))
val primes = 2 #:: oddPrimes
def isPrime(n: Int): Boolean = {
if (n < 5) (n | 1) == 3
else primes.takeWhile(_ <= math.sqrt(n)).forall(n % _ > 0)
}
val limit = primes.takeWhile(_ <= 1000).length
val number = (1 to limit).filter(index => {
val list = primes.take(index)
val sum = list.sum
val flag = isPrime(sum)
if (flag) println(f"$index%3d ${list.last}%3d $sum%5d")
flag
}).length
println(s"\nfound $number such primes")
▲}</syntaxhighlight>
{{out}}
<pre> 1 2 2
2 3 5
4 7 17
6 13 41
12 37 197
14 43 281
60 281 7699
64 311 8893
96 503 22039
100 541 24133
102 557 25237
108 593 28697
114 619 32353
122 673 37561
124 683 38921
130 733 43201
132 743 44683
146 839 55837
152 881 61027
158 929 66463
162 953 70241
found 21 such primes
</pre>
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