#!/usr/local/bin/perl

use strict;
use warnings;
use feature qw(say);
use Math::Prime::Util qw(is_prime);
use Math::BigInt;
$|=1;

## This is straight forward.
## In each interation of the loop, we remove the lowest number of the triple,
## and at the same time set the highest number to the sum of the previous 2
## lowest numbers
##
## If the number isn't prime OR the number is the same as the previous number
## then we restart the loop with redo, if not we display the number and
## continue until we have displayed the first 13 perrin primes.

say "\nWith normal ints (first 25)\n\n";
my ($r,$s,$t)=(3,0,2);
($r,$s,$t)=($s,$t,$r+$s), is_prime($t) && $t!=$s ? (say $t) : (redo) for 1..13;

## Now with big ints...
say "\n\nWith big ints (first 25)\n\n";

($r,$s,$t)=(3,0,Math::BigInt->new(2));
($r,$s,$t)=($s,$t,$r+$s), is_prime($t) && $t!=$s ? (fmt($_,$t)) : (redo) for 1..40;

say "\n";

sub fmt {
 my $idx = shift;
 $_ = reverse $_[0]; s{(\d{3})}{$1,}g; $_ = reverse $_; s{^,}{};
 my @t = split /,/;
 printf " %3d : ",$idx;
 if( @t == 1) {
   say sprintf "%3d\n", $t[0];
   return;
 }
 my $pref = sprintf "%3d,",shift @t;

 while(@t) {
   print $pref, join ',',splice @t,0,18;
   say @t ? ',' : '';
   $pref = '           ';
 }
 say '';
}