

A317549


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


3



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

1,3


COMMENTS

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 digitsize 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.


LINKS

JeanMarc Falcoz, Table of n, a(n) for n = 1..5004


EXAMPLE

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 2step rollercoaster 0 < 1 < 2 > 1 > 0 < 3 < 4 > 2 > 0 < 5 < 6 > 2 > 1 < 7 < 8 > 3 > 0...


CROSSREFS

A317548 (1step roller coaster)
Sequence in context: A171659 A060466 A243992 * A239083 A239084 A322000
Adjacent sequences: A317546 A317547 A317548 * A317550 A317551 A317552


KEYWORD

nonn,base,look


AUTHOR

Eric Angelini and JeanMarc Falcoz, Aug 02 2018


STATUS

approved



