



1, 2, 2, 2, 1, 1, 2, 2, 1, 2, 1, 1, 2, 2, 2, 1, 1, 2, 1, 2, 2, 1, 1, 1, 1, 2, 1, 2, 2, 1, 2, 2, 1, 1, 2, 1, 2, 1, 2, 2, 1, 2, 2, 1, 1, 2, 1, 1, 2, 2, 1, 2, 1, 1, 2, 2, 2, 1, 2, 2, 1, 1, 2, 1, 1, 2, 2, 1, 2, 1, 1, 2, 1, 2, 2, 1, 1, 2, 1, 1, 2, 1, 2, 2, 1, 1, 2, 2, 1, 2, 2, 1, 1, 2, 1, 2, 2, 1, 2, 1, 1, 2, 2, 1, 2
(list;
table;
graph;
refs;
listen;
history;
text;
internal format)



OFFSET

1,2


COMMENTS

(1) Does every row occur infinitely many times as a segment of A000002?
(2) In Kolakoski's note, the initial 1 appears at the bottom, centered, with 2 just above and successive rows arise as branches so that the array resembles a handheld fan.
Arises from the Kolakoski sequence, K(n)=A000002(n), as follows:
row 1: 1
row 2: 2
row 3: 2 2
row 4: 1 1 2 2
row 5: 1 2 1 1 2 2,
and so on, where the first term in row n is K(n) and row n1 tells how many of each kind (1 or 2) to write in row n.


REFERENCES

William G. Kolakoski, unpublished note entitled "Kolakoski Series Fan," dated Nov 12, 1993.


LINKS

Table of n, a(n) for n=1..105.
Wikipedia, Kolakoski sequence


EXAMPLE

Row 4 (1,1,2,2) determines row 5: (one 1, one 2, two 1's, two 2's).


CROSSREFS

Cf. A000002.
Sequence in context: A062246 A037811 A091237 * A214774 A320107 A190321
Adjacent sequences: A143474 A143475 A143476 * A143478 A143479 A143480


KEYWORD

nonn,tabl


AUTHOR

Clark Kimberling, Aug 19 2008, Aug 25 2008


STATUS

approved



