Monotonic ordering of nonnegative differences 10^i-5^j, for 40>= i>=0, j>=0.

Terms

a(0) =0a(1) =5a(2) =9a(3) =75a(4) =95a(5) =99a(6) =375a(7) =875a(8) =975a(9) =995a(10) =999a(11) =6875a(12) =9375a(13) =9875a(14) =9975a(15) =9995a(16) =9999a(17) =21875a(18) =84375a(19) =96875a(20) =99375a(21) =99875a(22) =99975a(23) =99995a(24) =99999a(25) =234375a(26) =609375a(27) =921875a(28) =984375a(29) =996875