A276105 Lexicographically first sequence (with no duplicate term) where all the digits "2" are separated by two digits.

1, 2, 3, 4, 20, 5, 21, 6, 23, 7, 24, 8, 25, 9, 26, 12, 10, 27, 32, 11, 28, 42, 13, 29, 52, 14, 200, 201, 203, 204, 205, 206, 207, 208, 209, 210, 211, 213, 214, 215, 216, 217, 218, 219, 230, 231, 233, 234, 235, 236, 237, 238, 239, 240, 241, 243, 244, 245, 246, 247, 248, 249

Offset

1,2

Comments

The sequence is started with a(1)=1 and always extended with the smallest integer not yet used that does not lead to a contradiction.

Links

Table of n, a(n) for n=1..62.

Example

To match the infinite digit-pattern 2..2..2..2..2..2.. (etc.) one must use the integer 20 after the fourth term (which is 4), then use the integer 5, then use the integer 21, then use the integer 6, then use the integer 23 (as 22 is forbidden: no integer with consecutive 2's is allowed), etc.

Crossrefs

Sequence in context: A058772 A227941 A250259 * A247574 A169901 A012285

Adjacent sequences: A276102 A276103 A276104 * A276106 A276107 A276108

Keyword

nonn,base

Author

Eric Angelini, Aug 18 2016

Status

approved