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.

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A206446 Positions of 1 in A076478; complement of A206445.

Original entry on oeis.org

2, 6, 7, 9, 10, 16, 18, 21, 22, 23, 26, 28, 29, 30, 32, 33, 34, 42, 45, 49, 50, 52, 56, 58, 60, 61, 64, 65, 66, 67, 71, 74, 75, 77, 79, 81, 82, 83, 84, 87, 88, 90, 91, 92, 93, 95, 96, 97, 98, 108, 112, 117, 118, 121, 126, 128, 131, 132, 136, 137, 138, 140, 145
Offset: 1

Views

Author

Clark Kimberling, Feb 08 2012

Keywords

Examples

			The positions of 1 in 0,1,0,0,0,1,1,0,1,1,0,0,0,0,0,1,...
are 2,6,7,9,10,16,...
		

Crossrefs

Programs

  • Mathematica
    d[n_] := Rest@IntegerDigits[n + 1, 2] + 1;
    t = -1 + Flatten[Array[d, 100]]
    Flatten[Position[t, 0]]  (* A206445 *)
    Flatten[Position[t, 1]]  (* A206446 *)

A277914 a(n) is the number of zeros minus the number of ones among the first n terms of A076478.

Original entry on oeis.org

0, 1, 0, 1, 2, 3, 2, 1, 2, 1, 0, 1, 2, 3, 4, 5, 4, 5, 4, 5, 6, 5, 4, 3, 4, 5, 4, 5, 4, 3, 2, 3, 2, 1, 0, 1, 2, 3, 4, 5, 6, 7, 6, 7, 8, 7, 8, 9, 10, 9, 8, 9, 8, 9, 10, 11, 10, 11, 10, 11, 10, 9, 10, 11, 10, 9, 8, 7, 8, 9, 10, 9, 10, 11, 10, 9, 10, 9, 10, 9, 10
Offset: 0

Views

Author

Rémy Sigrist, Nov 03 2016

Keywords

Comments

A036799 gives the positions of zeros in this sequence.
Between two zeros, the graph of the sequence looks like a Takagi (or blancmange) curve.

Crossrefs

Programs

  • Mathematica
    Join[{0},Flatten[Array[Accumulate[Flatten[Tuples[{1,-1},#]]]&,5]]] (* Paolo Xausa, Dec 08 2023 *)

Formula

a(n) = Sum_{i=0..n-1} (-1)^A076478(i) for any n>=0.

A346306 Position in A076478 of the binary complement of the n-th word in A076478.

Original entry on oeis.org

2, 1, 6, 5, 4, 3, 14, 13, 12, 11, 10, 9, 8, 7, 30, 29, 28, 27, 26, 25, 24, 23, 22, 21, 20, 19, 18, 17, 16, 15, 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, 32, 31, 126, 125, 124, 123
Offset: 1

Views

Author

Clark Kimberling, Aug 16 2021

Keywords

Comments

Permutation of the positive integers obtained by reversing their order within successive subsets of length 2, 4, 8, 16, ... - Paolo Xausa, Mar 09 2023

Examples

			The first fourteen words w(n) are 0, 1, 00, 01, 10, 11, 000, 001, 010, 011, 100, 101, 110, 111, so that a(3) = 6.
From _Paolo Xausa_, Mar 09 2023: (Start)
Written as an irregular triangle, where row r >= 1 has length 2^r and row sum is A103897(r), the sequence begins:
   2,  1;
   6,  5,  4,  3;
  14, 13, 12, 11, 10,  9,  8,  7;
  30, 29, 28, 27, 26, 25, 24, 23, 22, 21, 20, 19, 18, 17, 16, 15;
  ... (End)
		

Crossrefs

Programs

  • Mathematica
    (See A007931.)
    A346306[rowmax_]:=Table[Range[2^(r+1)-2,2^r-1,-1],{r,rowmax}]; A346306[6] (* Paolo Xausa, Mar 09 2023 *)
  • Python
    from itertools import product
    def comp(s): z, o = ord('0'), ord('1'); return s.translate({z:o, o:z})
    def wgen(maxdigits):
        for digits in range(1, maxdigits+1):
            for b in product("01", repeat=digits):
                yield "".join(b)
    def auptod(maxdigits):
        w = [None] + [wn for wn in wgen(maxdigits)]
        return [w.index(comp(w[n])) for n in range(1, 2**(maxdigits+1) - 1)]
    print(auptod(6)) # Michael S. Branicky, Sep 03 2021

Formula

a(n) = 3*(2^d - 1) - n, where 2^d - 1 <= n <= 2^(d+1) - 2. - Michael S. Branicky, Sep 03 2021

A346309 Positions of words in A076478 such that #0's - #1's is odd.

Original entry on oeis.org

1, 2, 7, 8, 9, 10, 11, 12, 13, 14, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 127, 128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144, 145
Offset: 1

Views

Author

Clark Kimberling, Aug 28 2021

Keywords

Examples

			The first fourteen words w(n) are 0, 1, 00, 01, 10, 11, 000, 001, 010, 011, 100, 101, 110, 111, so that a(3) = 7.
		

Crossrefs

Cf. A007931, A076478, A346310 (complement), A053754.

Programs

Formula

a(n) = A053754(n+1) + 1, conjectured.

A346310 Positions of words in A076478 such that #0's - #1's is even.

Original entry on oeis.org

3, 4, 5, 6, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106
Offset: 1

Views

Author

Clark Kimberling, Aug 28 2021

Keywords

Examples

			The first fourteen words w(n) are 0, 1, 00, 01, 10, 11, 000, 001, 010, 011, 100, 101, 110, 111, so that a(1) = 3.
		

Crossrefs

Cf. A007931, A076478, A346309 (complement), A053738.

Programs

Formula

a(n) = A053738(n+1) - 1, conjectured.

A271728 Numbers n such that A076478(n)=1.

Original entry on oeis.org

1, 5, 6, 8, 9, 15, 17, 20, 21, 22, 25, 27, 28, 29, 31, 32, 33, 41, 44, 48, 49, 51, 55, 57, 59, 60, 63, 64, 65, 66, 70, 73, 74, 76, 78, 80, 81, 82, 83, 86, 87, 89, 90, 91, 92, 94, 95, 96, 97, 107, 111, 116, 117, 120, 125, 127, 130
Offset: 1

Views

Author

Gabriel Conant, Apr 13 2016

Keywords

Comments

By definition, this sequence enumerates a 'universal' set S of nonnegative integers: meaning that every finite binary sequence occurs as a consecutive subsequence of the characteristic function of S (viewed as an infinite binary sequence). The infinite graph with vertex set the integers and edge relation '|x-y| in S' is a countable random graph.

Crossrefs

Cf. A076478.

A346307 Number of runs in the n-th word in A076478.

Original entry on oeis.org

1, 1, 1, 2, 2, 1, 1, 2, 3, 2, 2, 3, 2, 1, 1, 2, 3, 2, 3, 4, 3, 2, 2, 3, 4, 3, 2, 3, 2, 1, 1, 2, 3, 2, 3, 4, 3, 2, 3, 4, 5, 4, 3, 4, 3, 2, 2, 3, 4, 3, 4, 5, 4, 3, 2, 3, 4, 3, 2, 3, 2, 1, 1, 2, 3, 2, 3, 4, 3, 2, 3, 4, 5, 4, 3, 4, 3, 2, 3, 4, 5, 4, 5, 6, 5, 4
Offset: 1

Views

Author

Clark Kimberling, Aug 16 2021

Keywords

Examples

			The first fourteen words w(n) are 0, 1, 00, 01, 10, 11, 000, 001, 010, 011, 100, 101, 110, 111, so that a(9) = 3.
		

Crossrefs

Programs

A362599 The terms of the n-th row of A076478 first appear from position a(n) in A362240.

Original entry on oeis.org

1, 2, 3, 1, 2, 5, 7, 3, 1, 4, 2, 10, 5, 12, 16, 7, 8, 3, 1, 9, 4, 11, 6, 2, 20, 10, 5, 24, 13, 12, 28, 16, 7, 33, 38, 8, 3, 43, 26, 1, 19, 9, 4, 23, 44, 11, 15, 6, 37, 2, 25, 20, 22, 10, 5, 36, 24, 46, 13, 45, 12, 53, 28, 31, 16, 32, 58, 7, 33, 42, 38, 64, 18
Offset: 0

Views

Author

Rémy Sigrist, Apr 27 2023

Keywords

Examples

			The first terms, alongside the corresponding row of A076478, are:
  n   a(n)  n-th row of A076478
  --  ----  --------------------
   0     1  0
   1     2   1
   2     3    00
   3     1  01
   4     2   10
   5     5      11
   6     7        000
   7     3    001
   8     1  010
   9     4     011
  10     2   100
   .     .  .
  A362240   010011000...
		

Crossrefs

Programs

  • Perl
    See Links section.

A308705 Decimal expansion of the constant formed by concatenating the terms of A076478 (binary vectors of lengths 1, 2, 3, ... in numerical order).

Original entry on oeis.org

2, 7, 6, 3, 8, 7, 1, 1, 7, 2, 7, 9, 4, 8, 6, 5, 2, 3, 7, 3, 4, 1, 9, 8, 6, 7, 6, 2, 1, 1, 9, 0, 1, 2, 3, 0, 5, 5, 5, 0, 8, 9, 9, 8, 8, 1, 6, 0, 6, 8, 5, 5, 0, 6, 1, 4, 3, 6, 7, 6, 8, 1, 9, 1, 1, 5
Offset: 0

Views

Author

David McFadzean, Jun 18 2019

Keywords

Comments

The binary vectors "0,1,00,01,10,11,000,001,..." are concatenated into a constant "0.0100011011000001...", then converted to decimal.

Examples

			0.276387117279486523734198676211901230555089988160685506143676819115...
		

Crossrefs

Cf. A076478.

Programs

  • Mathematica
    m = 100; d[n_] := Rest@IntegerDigits[n + 1, 2] + 1; v = Flatten[Array[d, 4 m]] - 1; RealDigits[FromDigits[v, 2]/2^Length[v], 10, m][[1]] (* Amiram Eldar, Jul 05 2019 after Clark Kimberling at A076478 *)
  • Python
    from bigfloat import *
    import string
    def GenerateBitstring(bitstring, suffix, recurse):
        if recurse == 0:
            bitstring = bitstring + suffix
        else:
            bitstring = GenerateBitstring(bitstring, suffix + "0", recurse-1)
            bitstring = GenerateBitstring(bitstring, suffix + "1", recurse-1)
        return bitstring
    VulcanBinary = ""
    MaxRecursion = 8
    for i in range(1,MaxRecursion+1):
        VulcanBinary = GenerateBitstring(VulcanBinary, "", i)
    print('.' + VulcanBinary)
    with precision(2000):
        VulcanDecimal = BigFloat(0)
        b = BigFloat(1)
        for c in VulcanBinary:
            b = b/2.
            if c == '1':
                VulcanDecimal = VulcanDecimal+b
    print(VulcanDecimal)
    print(string.join(x + ',' for x in str(VulcanDecimal)[2:]))

A030190 Binary Champernowne sequence (or word): write the numbers 0,1,2,3,4,... in base 2 and juxtapose.

Original entry on oeis.org

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

Views

Author

Keywords

Comments

a(A003607(n)) = 0 and for n > 0: a(A030303(n)) = 1. - Reinhard Zumkeller, Dec 11 2011
An irregular table in which the n-th row lists the bits of n (see the example section). - Jason Kimberley, Dec 07 2012
The binary Champernowne constant: it is normal in base 2. - Jason Kimberley, Dec 07 2012
This is the characteristic function of A030303, which gives the indices of 1's in this sequence and has first differences given by A066099. - M. F. Hasler, Oct 12 2020

Examples

			As an array, this begins:
0,
1,
1, 0,
1, 1,
1, 0, 0,
1, 0, 1,
1, 1, 0,
1, 1, 1,
1, 0, 0, 0,
1, 0, 0, 1,
1, 0, 1, 0,
1, 0, 1, 1,
1, 1, 0, 0,
1, 1, 0, 1,
1, 1, 1, 0,
1, 1, 1, 1,
1, 0, 0, 0, 0,
1, 0, 0, 0, 1,
...
		

References

  • Michel Rigo, Formal Languages, Automata and Numeration Systems, 2 vols., Wiley, 2014. Mentions this sequence - see "List of Sequences" in Vol. 2.

Crossrefs

Cf. A007376, A003137, A030308. Same as and more fundamental than A030302, but I have left A030302 in the OEIS because there are several sequences that are based on it (A030303 etc.). - N. J. A. Sloane.
a(n) = T(A030530(n), A083652(A030530(n))-n-1), T as defined in A083651, a(A083652(k))=1.
Tables in which the n-th row lists the base b digits of n: this sequence and A030302 (b=2), A003137 and A054635 (b=3), A030373 (b=4), A031219 (b=5), A030548 (b=6), A030998 (b=7), A031035 and A054634 (b=8), A031076 (b=9), A007376 and A033307 (b=10). - Jason Kimberley, Dec 06 2012
A076478 is a similar sequence.
For run lengths see A056062; see also A318924.
See also A066099 for (run lengths of 0s) + 1 = first difference of positions of 1s given by A030303.

Programs

  • Haskell
    import Data.List (unfoldr)
    a030190 n = a030190_list !! n
    a030190_list = concatMap reverse a030308_tabf
    -- Reinhard Zumkeller, Jun 16 2012, Dec 11 2011
    
  • Magma
    [0]cat &cat[Reverse(IntegerToSequence(n,2)):n in[1..31]]; // Jason Kimberley, Dec 07 2012
    
  • Mathematica
    Flatten[ Table[ IntegerDigits[n, 2], {n, 0, 26}]] (* Robert G. Wilson v, Mar 08 2005 *)
    First[RealDigits[ChampernowneNumber[2], 2, 100, 0]] (* Paolo Xausa, Jun 16 2024 *)
  • PARI
    A030190_row(n)=if(n,binary(n),[0]) \\ M. F. Hasler, Oct 12 2020
    
  • Python
    from itertools import count, islice
    def A030190_gen(): return (int(d) for m in count(0) for d in bin(m)[2:])
    A030190_list = list(islice(A030190_gen(),30)) # Chai Wah Wu, Jan 07 2022
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