A275308 Starting terms for the second half of the Kolakoski sequence.

2, 1, 2, 2, 2, 1, 2, 2, 1, 1, 2, 2, 1, 2, 1, 1, 2, 2, 2, 2, 2, 1, 2, 1, 2, 2, 2, 2, 1, 1, 1, 2, 1, 1, 2, 1, 1, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 1, 2, 1, 1, 1, 2, 1, 2, 2, 1, 2, 2, 2, 1, 1, 2, 2, 2, 1, 2, 1, 1, 1, 2, 2, 2, 2, 1, 2, 1, 1, 1, 1, 2, 1, 1, 1, 1, 2, 1

Offset

1,1

Comments

When building the Kolakoski sequence (A000002) using substitutional generation, this is the first term that comes from the second 2. Or equivalently, this is the first new term added to the previous sequence.

Links

Table of n, a(n) for n=1..87.

Formula

a(n) = 1 + (A001083(n+1) mod 2) for n > 1. - Andrei Zabolotskii, Oct 03 2025

Example

.   22
.    ^
.   2211
.     ^
.   221121
.       ^
.   221121221
.         ^
.   22112122122112
.            ^
To obtain the first 5 terms: 2, 1, 2, 2, 2.

Crossrefs

Cf. A000002, A001083.

Sequence in context: A101422 A359938 A070304 * A233138 A214708 A083952

Adjacent sequences: A275305 A275306 A275307 * A275309 A275310 A275311

Keyword

nonn

Author

David Spies, Jul 22 2016

Extensions

Terms a(51) and beyond added by Andrei Zabolotskii, Oct 03 2025

Status

approved