A022303 - OEIS

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A022303

The sequence a of 1's and 2's starting with (1,2,1) such that a(n) is the length of the (n+2)nd run of a.

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

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,2

LINKS

Clark Kimberling, Table of n, a(n) for n = 1..20000

EXAMPLE

a(1) =1, so the 3rd run has length 1, so a(4) must be 2.

a(2) = 2, so the 4th run has length 2, so a(5) = 2 and a(6) = 1.

a(3) = 1, so the 5th run has length 1, so a(7) = 2.

a(4) = 2, so the 6th run has length 2, so a(8) = 1 and a(9) = 1.

Globally, the runlength sequence of a is 1,1,1,2,1,2,2,1,2,2,1,1,2,1,...., and deleting the first two terms leaves a = A022303.

MATHEMATICA