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Between two successive digits "4" there are 0, then 1, then 2, then 3, ... other digits.
1

%I #9 Dec 02 2016 09:55:08

%S 0,1,2,3,4,40,41,5,42,6,7,43,8,9,14,10,11,24,12,13,15,45,16,17,18,46,

%T 19,20,21,34,22,23,25,26,54,27,28,29,30,31,47,32,33,35,36,37,48,38,39,

%U 50,51,52,64,53,55,56,57,58,59,74,60,61,62,63,65,66,67,49,68,69,70,71,72,73,75,400,76,77,78,79,80,81,82,401,83,85,86,87,88,89,90,84,91,92,93,95,96,97,98,99,104,100,101,102,103,105,106,94,107,108,109

%N Between two successive digits "4" there are 0, then 1, then 2, then 3, ... other digits.

%C 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.

%H Jean-Marc Falcoz, <a href="/A278939/b278939.txt">Table of n, a(n) for n = 1..1056</a>

%e There are 0 digit between "4" and "40"; there is 1 digit between the "4" of "40" and the "4" of "41" (this is the "0" of "40"); there are 2 digits between the "4" of "41" and the "4" of "42" (they are the "1" of "41" and the "5" of "5"); there are 3 digits between the "4" of "42" and the "4" of "43" (they are the "2" of "42", the "6" of "6" and the "7" of "7"); etc.

%K nonn,base

%O 1,3

%A _Eric Angelini_ and _Jean-Marc Falcoz_, Dec 02 2016