OFFSET
1,2
COMMENTS
The sequence starts with a(1) = 0 and is always extended with the smallest integer not yet present that does not lead to a contradiction.
LINKS
Jean-Marc Falcoz, Table of n, a(n) for n = 1..4160
EXAMPLE
As a(1) = 0, we cannot have for a(2) an integer starting with an odd digit; we then extend the sequence with a(2) = 2; this meads that the next 2 digits must be odd; we thus have a(3) = 1 and a(4) = 3, which are the smallest available integers not yet present in the sequence; a(5) = 4 as a(5) cannot start with an odd digit; this value implies that the next 4 digits must be odd; we thus have a(6) = 5, a(7) = 7, a(8) = 9 and a(9) = 10 -- this integer being the smallest available one that doen't lead to a contradiction; a(10) cannot start with an odd digit as the digit "1" in the previous term "10" is already followed by an even digit ("0"); thus a(10) = 6; etc.
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Eric Angelini and Jean-Marc Falcoz, Oct 19 2016
STATUS
approved