A277677 Each even term "t" of the sequence is followed by t odd terms and each even digit "k" of the sequence is followed by k odd digits.

0, 2, 1, 3, 4, 5, 7, 9, 121, 10, 21, 123, 125, 127, 129, 141, 11, 143, 13, 145, 1110, 23, 147, 15, 149, 17, 161, 19, 31, 163, 33, 35, 165, 37, 39, 167, 51, 53, 169, 55, 57, 181, 59, 71, 73, 183, 75, 77, 79, 185, 91, 93, 95, 187, 97, 99, 111, 25, 189, 113, 115, 321, 323, 325, 327, 329, 341, 117, 27, 343, 119, 29, 345

Offset

1,2

Comments

After a(1) = 0, the sequence is always extended with the smallest integer not yet present which does not lead to a contradiction.

In a private mail to Eric Angelini, Lars Blomberg wrote about the b-file: "Only the even terms 0, 2, 4, 10, 1110, 12, 110, 6, 8, 2110, 2112, 2114, 14, 16, 18, 1112, 112, 2116 [are in this b-file]; so the sequence will continue from 2116 on with 2116 odd numbers, then an even one, etc."

Links

Lars Blomberg, Table of n, a(n) for n = 1..8887

Example

There are respectively 0 odd terms after "0", then 2 odd terms after "2" (they are 1 and 3), then 4 odd terms after "4" (they are 5, 7, 9 and 121), then 10 odd terms after "10" (they are 221, 123, 125, 127, 129, 141, 11, 143, 13 and 145), etc.
But there are also respectively 0 odd digits after "0", then 2 odd digits after "2" (they are 1 and 3), then 4 odd digits after "4" (they are 4, 5, 7, 9 and 1), then 2 odd digits after the "2" of "121" (they are the last "1" of "121" and the starting "1" of "10"), then 0 odd digits after "0", then 2 odd digits after the "2" of "21" (they are the "1" of "21" and the starting "1" of 123), etc.

Crossrefs

Cf. A277623.

Sequence in context: A277383 A353730 A077159 * A075379 A308000 A029636

Adjacent sequences: A277674 A277675 A277676 * A277678 A277679 A277680

Keyword

nonn,base

Author

Eric Angelini and Lars Blomberg Oct 26 2016

Status

approved