শূন্যস্থান পূরণ করুন। 11, 10, _______, 100, 1001, 10000, 100001....

The series alternates: 11, 10, 101, 100, 1001, 1000, 10001 – each pair is 1…1 followed by 1…0, with one more zero each time. The blank is 101.