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A317548
Lexicographically first sequence of different terms, starting with a(1) = 0 and showing a 1-step roller coaster of digits (see the Comments section).
4
0, 2, 1, 3, 12, 13, 14, 15, 4, 5, 16, 17, 6, 7, 18, 19, 8, 9, 23, 24, 25, 26, 27, 28, 29, 34, 35, 36, 37, 38, 39, 45, 46, 47, 48, 49, 56, 57, 58, 59, 67, 68, 69, 78, 79, 89, 120, 10, 20, 21, 30, 31, 32, 40, 41, 42, 43, 50, 51, 52, 53, 54, 60, 61, 62, 63, 64, 65, 70, 71, 72, 73, 74, 75, 76, 80, 81, 82, 83, 84, 85, 86, 87, 90, 91
OFFSET
1,2
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 digit-size point of view, we could see it as a kind of roller coaster going up one step, than down one step, than up a again one step, etc.
2-step, 3-step,... 8-step, 9-step roller-coasters sequences will be added soon to the database.
This is not a derangement of the positive integers (completed with 0) as integers like 11, 100 or 123 will never appear.
LINKS
EXAMPLE
The sequence starts with 0,2,1,3,12,13,14,15,4,5,16... and indeed the digits form a kind of 1-step roller-coaster 0 < 2 > 1 < 3 > 1 < 2 > 1 < 3 > 1 < 4 > 1 < 4...
CROSSREFS
A289263 (Number of maximal roller coasters in all n! permutations of n elements), A317549 (2-step roller coaster), A317550 (3-step).
Sequence in context: A175243 A168217 A329025 * A320327 A366591 A007447
KEYWORD
nonn,base,look
AUTHOR
STATUS
approved