A317549 - OEIS

%I #6 Aug 02 2018 08:00:32

%S 0,1,2,10,3,4,20,5,6,21,7,8,30,12,101,9,31,23,102,32,13,42,14,52,15,

%T 62,16,72,17,82,18,92,123,103,43,24,53,25,63,26,73,27,83,28,93,124,

%U 104,54,34,64,35,65,36,74,37,84,38,94,125,40,19,41,29,50,39,51,45,105,75,46,76,47,85,48,95,126,106,86,56,87,57,96,58,97

%N Lexicographically first sequence of different terms, starting with a(1) = 0 and showing a 2-step roller coaster of digits (see the Comments section).

%C After the digit 0 that starts the sequence, we have the 2nd digit of the sequence that is > 0, then the 3rd digit that is > the 2nd digit, then the 4th digit that is < the 3rd digit, the 5th digit that is < the 4th digit, etc. Considering the sequence from the digit-size point of view, we could see it as a kind of roller coaster going up two steps, than down two steps, than up a again two steps, etc.

%H Jean-Marc Falcoz, <a href="/A317549/b317549.txt">Table of n, a(n) for n = 1..5004</a>

%e The sequence starts with 0,1,2,10,3,4,20,5,6,21,7,8,30,... and indeed the digits form a kind of 2-step roller-coaster 0 < 1 < 2 > 1 > 0 < 3 < 4 > 2 > 0 < 5 < 6 > 2 > 1 < 7 < 8 > 3 > 0...

%Y A317548 (1-step roller coaster)

%K nonn,base,look

%O 1,3

%A _Eric Angelini_ and _Jean-Marc Falcoz_, Aug 02 2018