A288945 Starting with a(1) = 1, a(n) = smallest nonnegative integer not yet in the sequence such that the first digit of a(n) is the last digit of a(n-1) plus or minus 1, with preference given to -1 when possible. The digit 0 is not allowed.

1, 2, 11, 21, 22, 12, 13, 23, 24, 3, 25, 4, 31, 26, 5, 41, 27, 6, 51, 28, 7, 61, 29, 8, 71, 211, 212, 14, 32, 15, 42, 16, 52, 17, 62, 18, 72, 19, 81, 213, 214, 33, 215, 43, 216, 53, 217, 63, 218, 73, 219, 82, 111, 221, 222, 112, 113, 223, 224, 34, 35, 44, 36, 54

Offset

1,2

Comments

If a(n-1) ends in 1, a(n) must begin with 2 (i.e., a forced increase by 1).

There are no numbers in the sequence with first digit 9.

Links

Table of n, a(n) for n=1..64.

Example

11 is followed by 21 in the sequence since it can't be followed by a number starting with 0.

Crossrefs

Cf. A288946.

Sequence in context: A336034 A081242 A071762 * A343450 A245500 A342945

Adjacent sequences: A288942 A288943 A288944 * A288946 A288947 A288948

Keyword

nonn,base

Author

Enrique Navarrete, Jun 19 2017

Status

approved