Strange unique prime triplets: Difference between revisions

</pre>

=={{header|AWK}}==

<lang AWK>

# syntax: GAWK -f STRANGE_UNIQUE_PRIME_TRIPLETS.AWK

# converted from Go

BEGIN {

main(29,1)

main(999,0)

exit(0)

}

function main(n,show, count,i,j,k,s) {

for (i=3; i<=n-4; i+=2) {

if (is_prime(i)) {

for (j=i+2; j<=n-2; j+=2) {

if (is_prime(j)) {

for (k=j+2; k<=n; k+=2) {

if (is_prime(k)) {

s = i + j + k

if (is_prime(s)) {

count++

if (show == 1) {

printf("%2d + %2d + %2d = %d\n",i,j,k,s)

}

}

}

}

}

}

}

}

printf("Unique prime triples 2-%d which sum to a prime: %'d\n\n",n,count)

}

function is_prime(x, i) {

if (x <= 1) {

return(0)

}

for (i=2; i<=int(sqrt(x)); i++) {

if (x % i == 0) {

return(0)

}

}

return(1)

}

</lang>

{{out}}

<pre>

3 + 5 + 11 = 19

3 + 5 + 23 = 31

3 + 5 + 29 = 37

3 + 7 + 13 = 23

3 + 7 + 19 = 29

3 + 11 + 17 = 31

3 + 11 + 23 = 37

3 + 11 + 29 = 43

3 + 17 + 23 = 43

5 + 7 + 11 = 23

5 + 7 + 17 = 29

5 + 7 + 19 = 31

5 + 7 + 29 = 41

5 + 11 + 13 = 29

5 + 13 + 19 = 37

5 + 13 + 23 = 41

5 + 13 + 29 = 47

5 + 17 + 19 = 41

5 + 19 + 23 = 47

5 + 19 + 29 = 53

7 + 11 + 13 = 31

7 + 11 + 19 = 37

7 + 11 + 23 = 41

7 + 11 + 29 = 47

7 + 13 + 17 = 37

7 + 13 + 23 = 43

7 + 17 + 19 = 43

7 + 17 + 23 = 47

7 + 17 + 29 = 53

7 + 23 + 29 = 59

11 + 13 + 17 = 41

11 + 13 + 19 = 43

11 + 13 + 23 = 47

11 + 13 + 29 = 53

11 + 17 + 19 = 47

11 + 19 + 23 = 53

11 + 19 + 29 = 59

13 + 17 + 23 = 53

13 + 17 + 29 = 59

13 + 19 + 29 = 61

17 + 19 + 23 = 59

19 + 23 + 29 = 71

Unique prime triples 2-29 which sum to a prime: 42

Unique prime triples 2-999 which sum to a prime: 241,580