Sum of primes in odd positions is prime: Difference between revisions
Sum of primes in odd positions is prime (view source)
Revision as of 13:45, 8 November 2021
, 2 years agoadd C
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Odd indexed primes 2-999: 11
</pre>
=={{header|C}}==
<lang c>#include<stdio.h>
#include<stdlib.h>
int isprime( int p ) {
int i;
if(p==2) return 1;
if(!(p%2)) return 0;
for(i=3; i*i<=p; i+=2) {
if(!(p%i)) return 0;
}
return 1;
}
int main( void ) {
int s=0, p, i=1;
for(p=2;p<=999;p++) {
if(isprime(p)) {
if(i%2) {
s+=p;
if(isprime(s)) printf( "%d %d %d\n", i, p, s );
}
i+=1;
}
}
return 0;
}</lang>
=={{header|Factor}}==
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