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 A098645 List the positions of all digits '1' in the sequence. This is the lexicographically earliest increasing sequence with this property. 12
 1, 3, 10, 20, 22, 31, 32, 33, 34, 35, 41, 51, 52, 53, 54, 55, 111, 112, 200, 210, 220, 222, 231, 1111, 2000, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2020, 2022, 2023, 2024, 2031, 10000, 20000, 20002, 20003, 20004, 20005, 20006, 20007, 20008, 20009 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS 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. 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 That sequence has by now been entered as A210415. - M. F. Hasler, Oct 08 2013 LINKS EXAMPLE The first digit of the sequence is a "1", the 3rd digit also, then the 10th, the 11th, etc. CROSSREFS Cf. A098670. See A114134 for another version. See also A210414-A210423. Sequence in context: A048343 A056789 A174476 * A089693 A194116 A208951 Adjacent sequences:  A098642 A098643 A098644 * A098646 A098647 A098648 KEYWORD base,easy,nonn AUTHOR Eric Angelini, Oct 27 2004 EXTENSIONS Entry revised by Eric Angelini and N. J. A. Sloane, Feb 03 2006. More terms from David Wasserman, Feb 26 2008 STATUS approved

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Last modified April 8 14:52 EDT 2020. Contains 333314 sequences. (Running on oeis4.)