Palindromic primes: Difference between revisions
Content added Content deleted
m (→{{header|REXX}}: changed the title for the output to reflect that the palindromic primes are in base ten.) |
|||
Line 577: | Line 577: | ||
=={{header|REXX}}== |
=={{header|REXX}}== |
||
<lang rexx>/*REXX program finds and displays palindromic primes for all N < 1,000. |
<lang rexx>/*REXX program finds and displays palindromic primes in base ten for all N < 1,000.*/ |
||
parse arg hi cols . /*obtain optional argument from the CL.*/ |
parse arg hi cols . /*obtain optional argument from the CL.*/ |
||
if hi=='' | hi=="," then hi= 1000 /*Not specified? Then use the default.*/ |
if hi=='' | hi=="," then hi= 1000 /*Not specified? Then use the default.*/ |
||
Line 583: | Line 583: | ||
call genP /*build array of semaphores for primes.*/ |
call genP /*build array of semaphores for primes.*/ |
||
w= max(8, length( commas(hi) ) ) /*max width of a number in any column. */ |
w= max(8, length( commas(hi) ) ) /*max width of a number in any column. */ |
||
title= ' palindromic primes in base ten that are < ' commas(hi) |
|||
if cols>0 then say ' index │'center(title, 1 + cols*(w+1) ) |
if cols>0 then say ' index │'center(title, 1 + cols*(w+1) ) |
||
if cols>0 then say '───────┼'center("", 1 + cols*(w+1), '─') |
if cols>0 then say '───────┼'center("", 1 + cols*(w+1), '─') |
||
finds= 0; idx= 1 /*define # of palindromic primes & idx.*/ |
finds= 0; idx= 1 /*define # of palindromic primes & idx.*/ |
||
$= /*a list of palindromic primes (so far)*/ |
$= /*a list of palindromic primes (so far)*/ |
||
do j=1 for hi; if \!.j then iterate /*Is this number not prime? Then skip.*/ /* ◄■■■■■■■■ a filter. */ |
do j=1 for hi; if \!.j then iterate /*Is this number not prime? Then skip.*/ /* ◄■■■■■■■■ a filter. */ |
||
if j\==reverse(j) then iterate /*Not a palindromic prime? " " */ /* ◄■■■■■■■■ a filter. */ |
if j\==reverse(j) then iterate /*Not a palindromic prime? " " */ /* ◄■■■■■■■■ a filter. */ |
||
finds= finds + 1 /*bump the number of palindromic primes*/ |
finds= finds + 1 /*bump the number of palindromic primes*/ |
||
if cols<0 then iterate /*Build the list (to be shown later)? */ |
if cols<0 then iterate /*Build the list (to be shown later)? */ |
||
Line 621: | Line 621: | ||
{{out|output|text= when using the default inputs:}} |
{{out|output|text= when using the default inputs:}} |
||
<pre> |
<pre> |
||
index │ |
index │ palindromic primes in base ten that are < 1,000 |
||
───────┼─────────────────────────────────────────────────────────────────────────────────────────── |
───────┼─────────────────────────────────────────────────────────────────────────────────────────── |
||
1 |
1 | 2 3 5 7 11 101 131 151 181 191 |
||
11 |
11 | 313 353 373 383 727 757 787 797 919 929 |
||
───────┴─────────────────────────────────────────────────────────────────────────────────────────── |
───────┴─────────────────────────────────────────────────────────────────────────────────────────── |
||
Found 20 palindromic primes that are < 1,000 |
Found 20 palindromic primes in base ten that are < 1,000 |
||
</pre> |
</pre> |
||
{{out|output|text= when using the input of: <tt> 100000 </tt>}} |
{{out|output|text= when using the input of: <tt> 100000 </tt>}} |
||
<pre> |
<pre> |
||
index │ |
index │ palindromic primes in base ten that are < 100,000 |
||
───────┼─────────────────────────────────────────────────────────────────────────────────────────── |
───────┼─────────────────────────────────────────────────────────────────────────────────────────── |
||
1 |
1 | 2 3 5 7 11 101 131 151 181 191 |
||
11 |
11 | 313 353 373 383 727 757 787 797 919 929 |
||
21 |
21 | 10,301 10,501 10,601 11,311 11,411 12,421 12,721 12,821 13,331 13,831 |
||
31 |
31 | 13,931 14,341 14,741 15,451 15,551 16,061 16,361 16,561 16,661 17,471 |
||
41 |
41 | 17,971 18,181 18,481 19,391 19,891 19,991 30,103 30,203 30,403 30,703 |
||
51 |
51 | 30,803 31,013 31,513 32,323 32,423 33,533 34,543 34,843 35,053 35,153 |
||
61 |
61 | 35,353 35,753 36,263 36,563 37,273 37,573 38,083 38,183 38,783 39,293 |
||
71 |
71 | 70,207 70,507 70,607 71,317 71,917 72,227 72,727 73,037 73,237 73,637 |
||
81 |
81 | 74,047 74,747 75,557 76,367 76,667 77,377 77,477 77,977 78,487 78,787 |
||
91 |
91 | 78,887 79,397 79,697 79,997 90,709 91,019 93,139 93,239 93,739 94,049 |
||
101 |
101 | 94,349 94,649 94,849 94,949 95,959 96,269 96,469 96,769 97,379 97,579 |
||
111 |
111 | 97,879 98,389 98,689 |
||
───────┴─────────────────────────────────────────────────────────────────────────────────────────── |
───────┴─────────────────────────────────────────────────────────────────────────────────────────── |
||
Found 113 palindromic primes that are < 100,000 |
Found 113 palindromic primes in base ten that are < 100,000 |
||
</pre> |
</pre> |
||