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A338802
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a(n) is the number of distinct k in the range 1..n such that A000002(k) = A000002(n+1-k).
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1
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1, 0, 1, 4, 3, 0, 5, 4, 3, 8, 5, 2, 11, 8, 1, 12, 11, 4, 11, 16, 5, 12, 15, 4, 13, 20, 7, 16, 23, 4, 17, 22, 9, 18, 23, 12, 23, 24, 7, 24, 27, 8, 25, 32, 15, 28, 29, 12, 29, 28, 15, 34, 31, 16, 37, 32, 15, 36, 31, 16, 41, 36, 19, 48, 37, 6, 51, 40, 9, 52, 43
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OFFSET
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1,4
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COMMENTS
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Graphically, we have a superposition of 3 curves; these correspond to the trisections (see scatterplot in Links section).
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LINKS
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EXAMPLE
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For n = 5:
- Kolakoski sequence (K) starts: 1, 2, 2, 1, 1,
- K(1) = K(5),
- K(2) <> K(4),
- K(3) = K(3),
- K(4) <> K(2),
- K(5) = K(1),
- so a(5) = 3.
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PROG
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(PARI) See Links section.
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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