Triplet of three numbers: Difference between revisions

=={{header|Ksh}}==

<lang ksh>

#!/bin/ksh

# numbers n such that n-1, n+3, and n+5 are all prime where: n < 6,000.

# # Variables:

#

integer MAX_n=6000

# # Functions:

#

# # Function _triplet(n, arr) build array of n-1, n+3, n+5

#

function _triplet {

typeset _n ; integer _n=$1

typeset _arr ; nameref _arr="$2"

_arr=( $((_n-1)) $((_n+3)) $((_n+5)) )

}

# # Function _isprime(n) return 1 for prime, 0 for not prime

#

function _isprime {

typeset _n ; integer _n=$1

typeset _i ; integer _i

(( _n < 2 )) && return 0

for (( _i=2 ; _i*_i<=_n ; _i++ )); do

(( ! ( _n % _i ) )) && return 0

done

return 1

}

######

# main #

######

for ((i=2; i<MAX_n; i++)); do

typeset -a arr

_triplet ${i} arr

for ((j=0; j<${#arr[*]}; j++)); do

_isprime ${arr[j]}

(( ! $? )) && unset arr && continue 2

done

oldIFS=${IFS}

IFS=\,

print "${i}: ${arr[*]}"

IFS=${oldIFS}

unset arr

done</lang>

{{out}}<pre>

8: 7,11,13

14: 13,17,19

38: 37,41,43

68: 67,71,73

98: 97,101,103

104: 103,107,109

194: 193,197,199

224: 223,227,229

278: 277,281,283

308: 307,311,313

458: 457,461,463

614: 613,617,619

824: 823,827,829

854: 853,857,859

878: 877,881,883

1088: 1087,1091,1093

1298: 1297,1301,1303

1424: 1423,1427,1429

1448: 1447,1451,1453

1484: 1483,1487,1489

1664: 1663,1667,1669

1694: 1693,1697,1699

1784: 1783,1787,1789

1868: 1867,1871,1873

1874: 1873,1877,1879

1994: 1993,1997,1999

2084: 2083,2087,2089

2138: 2137,2141,2143

2378: 2377,2381,2383

2684: 2683,2687,2689

2708: 2707,2711,2713

2798: 2797,2801,2803

3164: 3163,3167,3169

3254: 3253,3257,3259

3458: 3457,3461,3463

3464: 3463,3467,3469

3848: 3847,3851,3853

4154: 4153,4157,4159

4514: 4513,4517,4519

4784: 4783,4787,4789

5228: 5227,5231,5233

5414: 5413,5417,5419

5438: 5437,5441,5443

5648: 5647,5651,5653

5654: 5653,5657,5659

5738: 5737,5741,5743</pre>