56 lines
1.5 KiB
Awk
56 lines
1.5 KiB
Awk
# syntax: GAWK -f SEXY_PRIMES.AWK
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BEGIN {
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cutoff = 1000034
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for (i=1; i<=cutoff; i++) {
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n1 = i
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if (is_prime(n1)) {
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total_primes++
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if ((n2 = n1 + 6) > cutoff) { continue }
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if (is_prime(n2)) {
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save(2,5,n1 FS n2)
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if ((n3 = n2 + 6) > cutoff) { continue }
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if (is_prime(n3)) {
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save(3,5,n1 FS n2 FS n3)
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if ((n4 = n3 + 6) > cutoff) { continue }
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if (is_prime(n4)) {
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save(4,5,n1 FS n2 FS n3 FS n4)
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if ((n5 = n4 + 6) > cutoff) { continue }
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if (is_prime(n5)) {
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save(5,5,n1 FS n2 FS n3 FS n4 FS n5)
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}
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}
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}
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}
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if ((s[2] s[3] s[4] s[5]) !~ (n1 "")) { # check for unsexy
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save(1,10,n1)
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}
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}
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}
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printf("%d primes less than %s\n\n",total_primes,cutoff+1)
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printf("%d unsexy primes\n%s\n\n",c[1],s[1])
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printf("%d sexy prime pairs\n%s\n\n",c[2],s[2])
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printf("%d sexy prime triplets\n%s\n\n",c[3],s[3])
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printf("%d sexy prime quadruplets\n%s\n\n",c[4],s[4])
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printf("%d sexy prime quintuplets\n%s\n\n",c[5],s[5])
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exit(0)
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}
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function is_prime(x, i) {
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if (x <= 1) {
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return(0)
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}
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for (i=2; i<=int(sqrt(x)); i++) {
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if (x % i == 0) {
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return(0)
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}
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}
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return(1)
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}
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function save(key,nbr_to_keep,str) {
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c[key]++
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str = s[key] str ", "
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if (gsub(/,/,"&",str) > nbr_to_keep) {
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str = substr(str,index(str,",")+2)
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}
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s[key] = str
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}
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