

A302173


Lexicographically first sequence of distinct terms such that any set of three successive digits can be reordered as {d, d+1, d+2}, d being the smallest of the three digits.


7



0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 78, 67, 56, 45, 34, 23, 12, 31, 20, 120, 123, 42, 312, 342, 345, 64, 53, 423, 453, 456, 75, 645, 675, 678, 97, 86, 756, 786, 789, 7867, 89, 7897, 867, 564, 534, 231, 201, 234, 567, 897, 8675, 6453, 4231, 2012, 3120, 1201, 2312, 3123, 1231, 2342, 3423, 1234, 2345
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OFFSET

1,3


COMMENTS

As the digit 0 has no predecessor and the digit 9 has no successor here, sets of successive digits like {1,0,9} and {8,9,0} are forbidden.


LINKS

JeanMarc Falcoz, Table of n, a(n) for n = 1..624


EXAMPLE

Terms a(1) to a(10) are obvious;
a(11) is 78 because 78 is the smallest integer not yet in the sequence such that the elements of the sets {8,9,7} and {9,7,8} are three consecutive digits;
a(12) is 67 because 67 is the smallest integer not yet in the sequence such that the elements of the sets {7,8,6} and {8,6,7} are three consecutive digits;
a(13) is 56 because 56 is the smallest integer not yet in the sequence such that the elements of the sets {6,7,5} and {7,5,6} are three consecutive digits;
etc.


CROSSREFS

Cf. A228326 for the same idea with sets of two digits.
Sequence in context: A024662 A153670 A229184 * A024663 A272360 A288946
Adjacent sequences: A302170 A302171 A302172 * A302174 A302175 A302176


KEYWORD

nonn,base


AUTHOR

Eric Angelini and JeanMarc Falcoz, Apr 03 2018


STATUS

approved



