cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A191254 Fixed point of the morphism 0 -> 01, 1 -> 02, 2 -> 01.

Original entry on oeis.org

0, 1, 0, 2, 0, 1, 0, 1, 0, 1, 0, 2, 0, 1, 0, 2, 0, 1, 0, 2, 0, 1, 0, 1, 0, 1, 0, 2, 0, 1, 0, 1, 0, 1, 0, 2, 0, 1, 0, 1, 0, 1, 0, 2, 0, 1, 0, 2, 0, 1, 0, 2, 0, 1, 0, 1, 0, 1, 0, 2, 0, 1, 0, 2, 0, 1, 0, 2, 0, 1, 0, 1, 0, 1, 0, 2, 0, 1, 0, 2, 0, 1, 0, 2, 0, 1, 0, 1, 0, 1, 0, 2, 0, 1, 0, 1, 0, 1, 0, 2, 0, 1, 0, 1, 0, 1, 0, 2, 0, 1, 0, 2, 0, 1, 0, 2, 0, 1, 0, 1, 0, 1, 0, 2, 0, 1, 0, 1, 0, 1, 0, 2
Offset: 1

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Author

Clark Kimberling, May 28 2011

Keywords

Comments

For related sequences, see notes in the Mathematica program.
The asymptotic density of the occurrences of k = 0, 1 and 2 is 1/2, 1/3 and 1/6, respectively. The asymptotic mean of this sequence is 2/3. - Amiram Eldar, May 31 2024

Crossrefs

Positions of 0 or 2: A003159; positions of 0: A005408; positions of 1: A036554; positions of 2: A108269.

Programs

  • Mathematica
    t = Nest[Flatten[# /. {0 -> {0, 1}, 1 -> {0, 2}, 2 -> {0, 1}}] &, {0}, 9]  (* A191254 *)
    Flatten[Position[t, 0]]  (* A005408, the odds *)
    a = Flatten[Position[t, 1]] (* A036554 *)
    b = Flatten[Position[t, 2]] (* A108269 *)
    a/2 (* A003159 *)
    b/4 (* A003159 *)
  • PARI
    A191254(n) = if(n%2,0,if(valuation(n,2)%2,1,2)); \\ Antti Karttunen, Nov 06 2018

Formula

From Jianing Song, May 30 2024: (Start)
Recurrence: a(2n-1) = 0, a(2n) = 1, 2, 1 for a(n) = 0, 1, 2 respectively.
a(n) = 0 for odd n; a(n) = 1 for even n such that v2(n) is odd; a(n) = 2 for even n such that v2(n) is even, where v2(n) = A007814(n) is the 2-adic valuation of n. (End)