%N Replacing each term with its digital root generates the original sequence, digit by digit.
%C The sequence is started with a(1) = 1 and always extended with the smallest integer not yet present and not leading to a contradiction.
%C There is no digit "0" in the sequence as "0" cannot be a digital root.
%H Jean-Marc Falcoz, <a href="/A284030/b284030.txt">Table of n, a(n) for n = 1..10001</a>
%e After 1,2,3,4,5,6,7,8,9 we have the terms 19,18,28,17,11,26,37,16,46,55,..., whose digital roots are respectively 1,9,1,8,2,8,1,7,1,1,... These digits are precisely the ones used in the sequence, in that order.
%Y Cf. A010888 (digital root), A052382 (zeroless numbers).
%A _Eric Angelini_ and _Jean-Marc Falcoz_, Mar 24 2017