Least k such that the last n decimal digits of 2^k are all powers of 2.

Terms

a(0) =0a(1) =7a(2) =7a(3) =18a(4) =19a(5) =90a(6) =91a(7) =271a(8) =1751a(9) =18807a(10) =56589a(11) =56589a(12) =56589a(13) =56589a(14) =899791a(15) =899791a(16) =2814790a(17) =7635171a(18) =7635171a(19) =39727671a(20) =99530619a(21) =233093807a(22) =233093807a(23) =233093807a(24) =233093807