A273466 The successive numbers of digits between two "2"s in the sequence are given by the sequence itself.

0, 1, 2, 20, 21, 3, 23, 4, 5, 6, 7, 8, 9, 10, 11, 13, 14, 15, 16, 12, 17, 18, 19, 30, 31, 33, 34, 35, 36, 37, 32, 38, 42, 39, 40, 41, 43, 44, 45, 46, 47, 48, 49, 50, 52, 51, 53, 24, 54, 55, 25, 56, 57, 62, 58, 59, 60, 72, 61, 63, 64, 65, 26, 66, 67, 68, 69, 27, 70, 71, 73, 74, 82, 75, 76, 77, 78, 79, 92, 80, 81, 83, 84, 85, 86, 120, 87, 88, 89, 90, 91, 93, 121, 94, 95, 96, 97, 98, 99, 102, 100, 101, 103, 104, 105, 123, 106, 107, 108, 112, 109, 110, 111, 113, 114, 132, 115, 116, 117, 118, 119, 130, 28

Offset

1,3

Comments

This is the lexicographically first such sequence, starting with a(1)=0, that has always been extended with the smallest integer not already present in the sequence and not leading to a contradiction.

Links

Table of n, a(n) for n=1..123.

Example

There are 0 digits between the first two "2"s of the sequence: [0,1,2,20]; there is 1 digit between the next pair of "2"s: [20,21]; there are 2 digits between the next pair of "2"s: [21,3,23]; there are 20 digits between the next pair of "2"s:  [23,4,5,6,7,8,9,10,11,13,14,15,16,12]; etc. The numbers 0, 1, 2, 20,... rebuild the starting sequence.

Crossrefs

Sequence in context: A012739 A261753 A075031 * A278938 A303157 A338994

Adjacent sequences: A273463 A273464 A273465 * A273467 A273468 A273469

Keyword

nonn,base

Author

Eric Angelini and Lars Blomberg, May 23 2016

Status

approved