OFFSET
1,3
COMMENTS
This is the lexicographically first such sequence, starting with a(1)=0, that is always extended with the smallest integer not already present in the sequence and not leading to a contradiction.
EXAMPLE
There are 0 digits between the first two "7" of the sequence [0,1,2,3,4,5,6,7,70]; then there is 1 digit between the next pair of "7": [70,71]; then there are 2 digits between the next pair of "7": [71,8,72]; then there are 3 digits between the next pair of "7": [72,9,17]; then there are 4 digits between the next pair of "7": [17,10,11,73,]; then there are 5 digits between the next pair of "7": [73,12,13,74]; then there are 6 digits between the next pair of "7": [74,14,15,27], etc. The quantities 0, 1, 2, 3, 4, 5, 6,... rebuild the starting sequence. The next "gap" will contain 7 digits and the next one 70.
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Eric Angelini and Lars Blomberg, May 23 2016
STATUS
approved