If the chessboard is realy endless, the knight can move forever

I`ve got an error in php for trying to use a gmp-functions. Should I solve this without those functions?

Why i`m getting this? By this line $array[] = 0;
"Fatal error: Allowed memory size of 134217728 bytes exhausted (tried to allocate 134217736 bytes) in /home/codewarrior/run.php on line 7"

And now i cant see my own comment... I admite, it could be a spoiler, but why I, as autor, cant see it?

I used Euler's partition theorem, whitch i thought is the fastest, and got an Execution Timed Out (12000 ms) error in last "random" test.
Whats the trick?
https://pastebin.com/GU06rRk6

Expected: equal to SLJHGfBQMmAkoBzmQhiPjZrjtvay awsInkszRCaRvmGcRPdQbbwnYiehuahNrObHOdohcdOoIceqfzjOHSUkLgvxZLmay !
Actual: SLJHGfBQMmAkoBzmQhiPjZrjtvay awsInkszRCaRvmGcRPdQbbwnYiehuahNrObHOdohcdOoIceqfzjOHSUkLgvxZL�ay !

Plz explaint this to me, what mean that "�"?

Why i got an error in test2. It returns "R L" as needed/
public class Dubstep {
public static String SongDecoder (String song)
{
do{
song=song.replace("WUB"," ");
}while (song.indexOf("WUB")>0);
return song.trim();
}
}