I just found a pretty interesting prime here:
222227772222222222222222222272227277222222222222222722222722722222222222227227727222272222222222227272277722227722222222227722272272227272222222227722272227227227222222272272272227272227222222272227727272722222722222772722222777222222722222727772272222222222722222722727772222222222272222722722272222222222272222722722272222222222272222722722272222222222272222727722272222222222272222727772722272222222227222727272722722272222227722727772722222227222222772277272722222222722722722277227222722222722722272272222777272222272272227272277222777722277727772277722222222277772222777Or, if you rearrange it in a square:
222227772222222222222222
222272227277222222222222
222722222722722222222222
227227727222272222222222
227272277722227722222222
227722272272227272222222
227722272227227227222222
272272272227272227222222
272227727272722222722222
772722222777222222722222
727772272222222222722222
722727772222222222272222
722722272222222222272222
722722272222222222272222
722722272222222222272222
727722272222222222272222
727772722272222222227222
727272722722272222227722
727772722222227222222772
277272722222222722722722
277227222722222722722272
272222777272222272272227
272277222777722277727772
277722222222277772222777
As far as I know, this 576-digit number is prime (or have high probabilities to be prime according to the GNU Multiple Precision (GMP) library,
someone should independently verify if you have a copy of Mathematica or something just checked with Wolfram Cloud, it's prime). Now if you want to Ctrl-F this page and search for 7...
[spoiler=Now you wonder how the hell I did that? It's a secret~]
<?php// By [email protected]// Licensed under LiLiQ-R$im = imagecreatefromgif($argv[1]);$ix = imagesx($im);$iy = imagesy($im);function findprime($a,$b){ global $im,$ix,$iy; $s=""; for($y=0; $y<$iy; $y++) { for($x=0; $x<$ix; $x++) { $c=imagecolorat($im,$x,$y); $s.=($c>0)?$a:$b; } } return gmp_nextprime($s);}$r=array();for($a=1;$a<=9;$a++){ for($b=0;$b<=9;$b++) { $n = findprime($a,$b); $p = count(array_unique(str_split(gmp_strval($n)))); //echo $a." ".$b/*." ".gmp_sub($n, $s)*/." ".$p."\n"; if($p==2) { $z=array(); $z[]=$a; $z[]=$b; $r[]=$z; } }}for($i=0;$i<count($r);$i++){ echo $m=gmp_strval(findprime($r[$i][0],$r[$i][1]))."\n"; echo chunk_split($m,$ix);}
You must have GMP and GD installed in your PHP installation. Script should take about 45 seconds to run.
[/spoiler]
Of course, some of you will recognize the fact I was inspired by this video:
