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Between two successive digits "5" there are 0, then 1, then 2, then 3, ... other digits.
1

%I #6 Dec 12 2016 09:14:25

%S 0,1,2,3,4,5,50,51,6,52,7,8,53,9,10,54,11,12,56,13,14,15,16,17,18,25,

%T 19,20,21,22,57,23,24,26,27,58,28,29,30,31,35,32,33,34,36,37,45,38,39,

%U 40,41,42,43,59,44,46,47,48,49,60,500,61,62,63,64,66,67,501,68,69,70,71,72,73,65,74,76,77,78,79,80,81,82,502,83,84,86,87,88,89,90,75,91,92,93,94,96,97,98,99,105,100,101,102,103,104,106,85,107,108,109

%N Between two successive digits "5" 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="/A278940/b278940.txt">Table of n, a(n) for n = 1..1057</a>

%e There are 0 digit between "5" and "50"; there is 1 digit between the "5" of “50” and the "5" of "51" (this is the "0" of "50"); there are 2 digits between the "5" of "51" and the "5" of "52" (they are the "1" of "51" and the "6" of "6"); there are 3 digits between the "5" of "52" and the "5" of "53" (they are the "2" of "52", the "7" of "7" and the "8" of "8"); etc.

%K nonn,base

%O 1,3

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