Primitive cofactor of n-th repunit A002275(n).

Terms

a(0) =1a(1) =11a(2) =111a(3) =101a(4) =11111a(5) =91a(6) =1111111a(7) =10001a(8) =333667a(9) =9091a(10) =11111111111a(11) =9901a(13) =909091a(14) =90090991a(15) =100000001a(17) =999001a(19) =99009901a(20) =900900990991a(21) =826446281a(23) =99990001