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Palindromic primes: Difference between revisions
m
→{{header|REXX}}: changed comments.
m (→{{header|REXX}}: used a better algorithm for finding high prime.) |
m (→{{header|REXX}}: changed comments.) |
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Line 450:
if cols>0 then say '───────┼'center("" , 1 + cols*(w+1), '─')
finds= 0; idx= 1 /*define # of palindromic primes & idx.*/
$= /*
do j=1 for # /*search for palindromic primes. */
if @.j\==reverse(@.j) then iterate /*Not a palindromic prime? Then skip. */
Line 469:
commas: parse arg ?; do jc=length(?)-3 to 1 by -3; ?=insert(',', ?, jc); end; return ?
/*──────────────────────────────────────────────────────────────────────────────────────*/
genP: !.= 0;
@.1=2; @.2=3; @.3=5; @.4=7; @.5=11 /*define some low primes. */
!.2=1; !.3=1; !.5=1; !.7=1; !.11=1 /* " " " " flags. */
#=5; s.#= @.# **2 /*number of primes so far; prime². */
/* [↓] generate more primes ≤ high.*/
do j=@.#+2 by 2 to
parse var j '' -1 _; if _==5 then iterate /*J divisible by 5? (right dig)*/
if j// 3==0 then iterate /*" " " 3? */
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