A273885 Pick any pair of "7" digits in the sequence. Those two "7"s are separated by k digits. This is the lexicographically earliest sequence of distinct terms in which all the resulting values of k are distinct.

0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 38, 37, 39, 40, 41, 42, 43, 44, 45, 46, 48, 49, 50, 47, 51, 52, 53, 54, 55, 56, 58, 57, 59, 60, 61, 62, 63, 64, 65, 66, 68, 69, 70, 71, 80

Offset: 1

Author

Eric Angelini and Jean-Marc Falcoz, Jun 02 2016

Keywords

• nonn
• base

Comments

The sequence starts with a(1)=0. It is then always extended with the smallest integer not yet present and not leading to a contradiction (which would mean producing a value of k already seen).

Links

• Eric Angelini, Table of n, a(n) for n = 1..1011

Crossrefs

See A273376 for the equivalent sequence dealing with digit-"1" pairs instead of "7"