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A210423 List the positions of all digits 9 in the concatenation of all terms, not necessarily in order. This is the lexicographically earliest such sequence.

%I A210423 #19 Apr 18 2021 02:14:48
%S A210423 2,9,4,90,7,91,92,13,93,17,94,21,95,25,96,29,97,28,35,98,39,99,38,40,
%T A210423 47,900,52,901,57,902,62,903,67,904,72,905,77,906,82,907,87,908,999,
%U A210423 9999,9990,104,909,106,113,910,119,911,118,128,912,134,913,139,143
%N A210423 List the positions of all digits 9 in the concatenation of all terms, not necessarily in order. This is the lexicographically earliest such sequence.
%C A210423 See A210415 for comments, links, and code.
%H A210423 Danny Rorabaugh, <a href="/A210423/b210423.txt">Table of n, a(n) for n = 1..1000</a>
%e A210423 The sequence cannot start with 1 because the first digit is not 9. Let us start with 2: the second digit is equal to 9. The third digit cannot be 3 because the third digit is not 9. So let it be 4. In the next position we now have 90 because it is the minimum number greater than 8 and starting with the digit 9. And so on.
%Y A210423 Cf. A210414, A210415, A210416, A210417, A210418, A210419, A210420, A210421, A210422.
%K A210423 nonn,base
%O A210423 1,1
%A A210423 _Paolo P. Lava_, Mar 26 2012
%E A210423 a(23)-a(26) corrected by _Paolo P. Lava_, Apr 17 2012