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A137419 a(n) = (a(n - 4) + 1 - ((-1)^a(a(n - 1)) + 1)*(a(a(n - 1)) - a(a(n - 2)))/2). +0
1
1, 2, 2, 1, 2, 2, 3, 2, 3, 3, 4, 3, 3, 4, 5, 3, 4, 5, 5, 4, 5, 5, 6, 5, 6, 6, 7, 6, 8, 7, 8, 8, 9, 8, 10, 9, 10, 9, 11, 9, 11, 9, 12, 10, 12, 10, 13, 11, 12, 11, 13, 12, 13, 12, 14, 12, 14, 12, 15, 13, 15, 13, 16, 14, 15, 14, 18, 15, 16, 15, 19, 16, 17, 15, 20, 18, 18, 16, 21, 19, 19, 17, 23 (list; graph; listen)
OFFSET

1,2

COMMENT

A recursive chaotic sequence based on Bertran Steinsky's sequence.

I started with the sequence from Bertran Steinsky quoted in A000002:

a[1] = 1; a[2] = 2; a[3] = 2;

a[n_] := a[n] = a[n - 1] + 1 - ((-1)^a[a[n - 1]] + 1)*(a[n - 1] - a[n - 2])/2;

and worked to minimize it while getting a more chaotic result.

REFERENCES

Bertran Steinsky, A Recursive Formula for the Kolakoski Sequence A000002, J. Integer Sequences, Vol. 9 (2006), Article 06.3.7.

FORMULA

a(1) = 1; a(2) = 2; a(3) = 2; a(4) = 1; a(n) = (a(n - 4) + 1 - ((-1)^a(a(n - 1)) + 1)*(a(a(n - 1)) - a(a(n - 2)))/2)

MATHEMATICA

Clear[a] a[1] = 1; a[2] = 2; a[3] = 2; a[4] = 1; a[n_] := a[n] = (a[n - 4] + 1 - ((-1)^a[a[n - 1]] + 1)*(a[a[n - 1]] - a[a[n - 2]])/2); Table[a[n], {n, 1, 100}]

CROSSREFS

Cf. A000002.

Sequence in context: A029286 A050333 A143999 this_sequence A057536 A014420 A029289

Adjacent sequences: A137416 A137417 A137418 this_sequence A137420 A137421 A137422

KEYWORD

nonn

AUTHOR

Roger L. Bagula (rlbagulatftn(AT)yahoo.com), Apr 21 2008

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Last modified November 25 20:09 EST 2009. Contains 167514 sequences.


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