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.

Showing 1-2 of 2 results.

A280512 Index sequence of the Thue-Morse sequence (A010060, using offset 1) as a reverse block-fractal sequence.

Original entry on oeis.org

1, 3, 2, 1, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 48, 47, 46, 45, 44, 43, 42, 41, 40, 39, 38, 37, 36, 35, 34, 33, 32, 31, 30, 29, 28, 27, 26, 25, 24, 23, 22, 21, 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 192, 191, 190, 189, 188
Offset: 1

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Author

Clark Kimberling, Feb 10 2017

Keywords

Comments

See A280511 for definitions. Note that the records, 3,12,48,192,... are also records in A280510, if A010060 is indexed with offset 1 instead of 0; see Example.

Examples

			A010060 = (0,1,1,0,1,0,0,1,1,0,0,1,0,1,1,0,1,0,0,1,0,,...) = (s(1), s(2), ... ).
(init. bl. #1) = (0); reversal = (0), first occurs s(1), so that a(1) = 1;
(init. bl. #2) = (0,1); reversal = (1,0) first occurs at s(3), so that a(2) = 3;
(init. bl. #3) = (0,1,1); reversal = (1,1,0) first occurs s(2), so that a(3) = 2.
		

Crossrefs

Programs

  • Mathematica
    seq = Table[Mod[Length[FixedPointList[BitAnd[#, # - 1] &, n]], 2], {n, 0, 400}]  (* A010060 *)
    seq = StringJoin[Map[ToString, seq]]
    breverse[seq_] := Flatten[Last[Reap[NestWhile[# + 1 &, 1, (StringLength[
    str = StringTake[seq, Min[StringLength[seq], #]]] == # && ! (Sow[
    StringPosition[seq, StringReverse[str], 1][[1]][[1]]]) === {}) &]]]];
    breverse[seq] (* A280512 *) (* Peter J. C. Moses, Jan 01 2017 *)

A337909 Distinct terms of A080079 in the order in which they appear.

Original entry on oeis.org

1, 2, 4, 3, 8, 7, 6, 5, 16, 15, 14, 13, 12, 11, 10, 9, 32, 31, 30, 29, 28, 27, 26, 25, 24, 23, 22, 21, 20, 19, 18, 17, 64, 63, 62, 61, 60, 59, 58, 57, 56, 55, 54, 53, 52, 51, 50, 49, 48, 47, 46, 45, 44, 43, 42, 41, 40, 39, 38, 37, 36, 35, 34, 33, 128
Offset: 1

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Author

Keywords

Comments

This sequence is a permutation of the positive integers.
The cardinality of {2^k, ..., (2^k - 0^k)/2 + 1} is A011782(k).

Examples

			(2^0, ..., (2^0 - 0^0)/2 + 1) = (1),
(2^1, ..., (2^1 - 0^1)/2 + 1) = (2),
(2^2, ..., (2^2 - 0^2)/2 + 1) = (4, 3),
(2^3, ..., (2^3 - 0^3)/2 + 1) = (8, 7, 6, 5)...
		

Crossrefs

Programs

  • Mathematica
    {1}~Join~Array[3*2^(IntegerLength[# - 1, 2] - 1) - # + 1 &, 64, 2] (* Michael De Vlieger, Oct 05 2020 *)
  • PARI
    a(n) = if(n--, 3<Kevin Ryde, Sep 29 2020

Formula

a(1) = 1 and a(n) = A080079(n - 1 + 2^floor(log_2(n - 1))) if n > 1.
a(n) = A080079(A004761(n+1)).
From Kevin Ryde, Sep 29 2020: (Start)
a(n) = 3*A053644(n-1) - (n-1), if n > 1.
a(n) = A054429(n-1) + 1, if n > 1.
a(n) = A280510(n) - n + 1, if n > 1. (End)
Showing 1-2 of 2 results.