%I
%S 0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,
%T 26,27,28,29,30,31,32,33,35,34,36,37,38,39,40,41,50,51,42,52,43,53,55,
%U 56,57,58,59,60,61,62,63,65,45,66,67,68,69,70,54,71,46,72,73,75,76,77,78,79
%N Pick any pair of "4" digits in the sequence. Those two "4"s are separated by k digits. This is the lexicographically earliest sequence of distinct terms in which all the resulting values of k are distinct.
%C The sequence starts with a(1)=0. It is then always extended with the smallest integer not yet present and not leading to a contradiction (which would mean producing a value of k already seen).
%H Eric Angelini, <a href="/A273882/b273882.txt">Table of n, a(n) for n = 1..1011</a>
%Y See A273376 for the equivalent sequence dealing with digit"1" pairs instead of "4"
%K nonn,base
%O 1,3
%A _Eric Angelini_ and _JeanMarc Falcoz_, Jun 02 2016
