A108988 A (twin's digits) self-disappearing sequence.

1, 10, 110, 111, 112, 210, 220, 221, 331, 332, 442, 443, 553, 554, 664, 665, 775, 776, 886, 887, 997, 998, 1180, 2200, 2201, 2210, 3300, 3301, 3310, 4400, 4401, 4410, 5500, 5501, 5510, 6600, 6601, 6610, 7700, 7701, 7710, 8800, 8801, 8810, 9900, 9901, 9910

Offset

1,2

Comments

Two identical digits forming a pair disappear instantly, even if they belong to two successive integers [112 -> 2], [111 -> 1], [13,37 --> 1,7].

Links

Table of n, a(n) for n=1..47.

Example

This strictly increasing sequence begins with 1. The next integer must be the smallest one which makes disappear *all* the previous ones [thus after 1 put 10, leaving a single 0 after disappearance of the two 1's; now the smallest integer which makes disappear this 0 is 110 -- leaving nothing in the sequence; the next integer will be 111 -- because if a(n) erases all previous digits *and* all digits of a(n) itself, the next integer should be a(n)+1]

Crossrefs

Sequence in context: A281278 A281177 A280460 * A097257 A333723 A043996

Adjacent sequences: A108985 A108986 A108987 * A108989 A108990 A108991

Keyword

base,easy,nonn

Author

Eric Angelini, Jul 28 2005

Status

approved