OFFSET
1,3
COMMENTS
As the digit 0 has no predecessor and the digit 9 has no successor here, sets of successive digits like {5,4,3,2,1,0,9} and {4,5,6,7,8,9,0} are forbidden.
EXAMPLE
Terms a(1) to a(10) are obvious;
a(11) is 34 because 34 is the smallest integer not yet in the sequence such that the elements of the sets {4,5,6,7,8,9,3} and {5,6,7,8,9,3,4} are seven consecutive digits;
a(12) is 56 because 56 is the smallest integer not yet in the sequence such that the elements of the sets {6,7,8,9,3,4,5} and {7,8,9,3,4,5,6} are seven consecutive digits;
a(13) is 78 because 78 is the smallest integer not yet in the sequence such that the elements of the sets {8,9,3,4,5,6,7} and {9,3,4,5,6,7,8} are seven consecutive digits;
etc.
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Eric Angelini and Jean-Marc Falcoz, Apr 09 2018
STATUS
approved