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A270642 The sequence a of 1's and 2's starting with (1,1,2,2) such that a(n) is the length of the (n+2)nd run of a. 2
1, 1, 2, 2, 1, 2, 1, 1, 2, 2, 1, 2, 2, 1, 2, 1, 1, 2, 2, 1, 2, 2, 1, 1, 2, 1, 1, 2, 1, 2, 2, 1, 1, 2, 1, 1, 2, 2, 1, 2, 1, 1, 2, 1, 2, 2, 1, 2, 2, 1, 1, 2, 1, 2, 2, 1, 2, 1, 1, 2, 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 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,3
COMMENTS
See A270641 for a guide to related sequences.
LINKS
EXAMPLE
a(1) = 1, so the 3rd run has length 1, so a(5) must be 1.
a(2) = 1, so the 4th run has length 1, so a(6) = 2 and a(7) = 1.
a(3) = 2, so the 5th run has length 2, so a(8) = 1 and a(9) = 2.
a(4) = 2, so the 6th run has length 2, so a(10) = 2 and a(11) = 1.
Globally, the runlength sequence is 2,2,1,1,2,2,1,2,1,1,2,2,1,2,..., and deleting the first 2 terms leaves the same sequence.
MATHEMATICA
a = {1, 1, 2, 2}; Do[a = Join[a, ConstantArray[If[Last[a] == 1, 2, 1], {a[[n]]}]], {n, 200}]; a (* Peter J. C. Moses, Apr 01 2016 *)
CROSSREFS
Sequence in context: A001285 A088424 A317960 * A270643 A270647 A261126
KEYWORD
nonn,easy
AUTHOR
Clark Kimberling, Apr 06 2016
STATUS
approved

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Last modified April 21 14:03 EDT 2024. Contains 371870 sequences. (Running on oeis4.)