-snipped after solved
it->difficulty = pow(2, 5*(prefix.length()-4));
it->difficulty = pow(256, prefix.length() - 1);
./vanitygen 1tDifficulty: 1353./vanitygen 1TDifficulty: 1353./vanitygen -i 1t Difficulty: 676
./vanitygen 1toDifficulty: 78508./vanitygen 1ToDifficulty: 78508./vanitygen -i 1toDifficulty: 39254
./vanitygen 1tt Difficulty: 78508./vanitygen -i 1ttDifficulty: 19627./vanitygen 1tt 1TT 1tT 1TtNext match difficulty: 19627 (4 prefixes)
11: Difficulty: 256111: Difficulty: 655361111: Difficulty: 167772161111A: Difficulty: 259627881112: Difficulty: 133511a: Difficulty: 7850811R: Difficulty: 7850811RRa: Difficulty: 2641042241aa: Difficulty: 785081AA: Difficulty: 13301AAz: Difficulty: 771781zAA: Difficulty: 45535211AzA: Difficulty: 771781AA1AA: Difficulty: 2596278811zz1zz: Difficulty: 153180450091zz11z: Difficulty: 153180450091111zz: Difficulty: 8884466105381111AA: Difficulty: 150584171271ABCDE: Difficulty: 2596278811ABCDz: Difficulty: 2596278811oiL: Difficulty: 4553521
-snip
for prefix in `cat /tmp/list | cut -d' ' -f1`; do echo -n "$prefix: "; ./vanitygen -n $prefix | grep Diffi; done