%I #16 Dec 13 2019 13:38:53
%S 1,3,10,20,22,31,32,33,34,35,41,51,52,53,54,55,111,112,200,210,220,
%T 222,231,1111,2000,2002,2003,2004,2005,2006,2007,2008,2009,2020,2022,
%U 2023,2024,2031,10000,20000,20002,20003,20004,20005,20006,20007,20008,20009
%N List the positions of all digits '1' in the sequence. This is the lexicographically earliest increasing sequence with this property.
%C Start with a(1) = 1. For n > 1, choose a(n) to be the smallest number > a(n-1) consistent with the condition that "the a(n)-th digit is a 1 and no 1's occur in other positions" is true for all n.
%C If we change "> a(n-1)" to "not already used", we get 1, 3, 10, 6, 11, 7, 21, 13, 15, 17, 19, 101, ... - _David Wasserman_, Feb 26 2008
%C That sequence has by now been entered as A210415. - _M. F. Hasler_, Oct 08 2013
%H <a href="/index/Se#self-referencing_sequences">Index to the OEIS: Entries related to self-referencing sequences</a>.
%e The first digit of the sequence is a "1", the 3rd digit also, then the 10th, the 11th, etc.
%Y Cf. A098670. See A114134 for another version. See also A210414-A210423.
%K base,easy,nonn
%O 1,2
%A _Eric Angelini_, Oct 27 2004
%E Entry revised by Eric Angelini and _N. J. A. Sloane_, Feb 03 2006.
%E More terms from _David Wasserman_, Feb 26 2008