A284200 - OEIS

%I #10 Mar 23 2017 14:36:10

%S 0,1,10,100,2,110,20,3,21,11,120,4,200,5,30,22,12,13,14,15,210,6,40,

%T 220,50,7,51,300,8,23,24,16,25,17,31,18,41,19,52,26,130,9,60,400,32,

%U 42,70,35,80,27,45,61,33,90,101,81,28,34,29,43,106,62,55,71,37,53,91,111,82,44,121,39,65,72,92,36,112,310,49,46,102

%N The successive digits of the sequence are the same digits that have an odd rank in the sequence.

%C The sequence is started with a(1) = 0 and always extended with the smallest integer not yet present and not leading to a contradiction.

%H Jean-Marc Falcoz, <a href="/A284200/b284200.txt">Table of n, a(n) for n = 1..3003</a>

%e The first 15 terms are:

%e 0,1,10,100,2,110,20,3,21,11,120,4,200,5,30

%e Their successive digits are:

%e 0,1,1,0,1,0,0,2,1,1,0,2,0,3,2,1,1,1,1,2,0,4,2,0,0,5,3,0

%e The even rank digits are here (between parentheses):

%e 0,(1),1(0),1(0)0,(2),1(1)0,(2)0,(3),2(1),1(1),1(2)0,(4),2(0)0,(5),3(0),...

%e Erasing the digits in the parentheses:

%e 0,( ),1( ),1( )0,( ),1( )0,( )0,( ),2( ),1( ),1( )0,( ),2( )0,( ),3( ),...

%e The surviving digits are:

%e 0,1,1,0,1,0,0,2,1,1,0,2,0,3,...

%e Those are indeed the digits of the starting sequence.

%K nonn,base

%O 1,3

%A _Eric Angelini_ and _Jean-Marc Falcoz_, Mar 22 2017