2*(10^n-5), n>0.

A173813

2*(10^n-5), n>0.

Terms

    a(0) =10a(1) =190a(2) =1990a(3) =19990a(4) =199990a(5) =1999990a(6) =19999990a(7) =199999990a(8) =1999999990a(9) =19999999990a(10) =199999999990

External references