A083653 -id:A083653 - cp's OEIS frontend

A083654 Consider the binary Champernowne sequence (A030190): number of successive numbers to be concatenated beginning with A083653(n) such that in binary representation n is contained.

1, 1, 1, 2, 1, 2, 2, 2, 1, 2, 1, 2, 2, 3, 2, 2, 1, 2, 2, 2, 2, 2, 2, 3, 2, 3, 2, 3, 2, 3, 2, 2, 1, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3, 2, 3, 3, 2, 2, 3, 2, 4, 2, 3, 2, 3, 2, 3, 2, 2, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 2, 2, 2, 2, 3, 3, 3, 3, 2, 3, 3, 2, 2, 3, 2, 2, 2

Offset: 0

Reinhard Zumkeller, May 01 2003

a(2^k)=1, see A083655 for all numbers m with a(m)=1;

			n=24: '11000'=24 is a suffix of the concatenation of the first 8 numbers: '0'1'10'11'100'101'110'111'1000', therefore a(24)=2 and A083653(24)=7.

Cf. A030304, A007088.

A083655 Numbers which do not appear prematurely in the binary Champernowne word (A030190).

Original entry on oeis.org

0, 1, 2, 4, 8, 10, 16, 32, 36, 64, 128, 136, 256, 512, 528, 1024, 2048, 2080, 4096, 8192, 8256, 16384, 32768, 32896, 65536, 131072, 131328, 262144, 524288, 524800, 1048576, 2097152, 2098176, 4194304, 8388608, 8390656, 16777216, 33554432

Offset: 0

Reinhard Zumkeller, May 01 2003

In other words, numbers k whose binary expansion first appears in A030190 at its expected place, i.e., n appears first starting at position A296349(n). - N. J. A. Sloane, Dec 17 2017

a(n) are the Base 2 "Punctual Bird" numbers: write the nonnegative integers, base 2, in a string 011011100101110111.... Sequence gives numbers which do not occur in the string ahead of their natural place. - Graeme McRae, Aug 11 2007

Graeme McRae, Aug 11 2007, Table of n, a(n) for n = 0..113 - Corrected by _Rémy Sigrist_, Jun 14 2020
Index entries for linear recurrences with constant coefficients, signature (0,0,6,0,0,-8).

A000079 is a subsequence.
Cf. A030190, A030304, A007088, A131881, A132131.
For the complement, the "Early Bird" numbers, see A296365.

LinearRecurrence[{0,0,6,0,0,-8},{0,1,2,4,8,10,16,32,36},50] (* Harvey P. Dale, Aug 19 2020 *)

a(n)= if (n<=2, n, my (m=n\3); if (n%3==0, 2^(2*m), n%3==1, 2^(2*m+1), 2^m + 2^(2*m+1)))  \\ Rémy Sigrist, Jun 14 2020

concat(0, Vec(x*(1 + 2*x + 4*x^2 + 2*x^3 - 2*x^4 - 8*x^5 - 8*x^6 - 8*x^7) / ((1 - 2*x^3)*(1 - 4*x^3)) + O(x^40))) \\ Colin Barker, Jun 14 2020

a(n) = 2^((2*n+1)\3) + (n%3==2)<<(n\3) - (n<3) \\ Charles R Greathouse IV, Dec 16 2022

A083653(a(n))=a(n), A083654(a(n))=1.
a(0)=0, a(1)=1, a(2)=2; then for n>=1, a(3n)=2^(2n), a(3n+1)=2^(2n+1), a(3n+2)=2^(2n+1)+2^n. - Graeme McRae, Aug 11 2007
From Colin Barker, Jun 14 2020: (Start)
G.f.: x*(1 + 2*x + 4*x^2 + 2*x^3 - 2*x^4 - 8*x^5 - 8*x^6 - 8*x^7) / ((1 - 2*x^3)*(1 - 4*x^3)).
a(n) = 6*a(n-3) - 8*a(n-6) for n>8. (End)
a(n) = 2^floor(2*(n+2)/3-1) + (floor((n+1)/3)-floor(n/3))*2^(floor(n/3)) - floor(5/(n+3)). - Alan Michael Gómez Calderón, Dec 15 2022

More terms from Graeme McRae, Aug 11 2007

A345672 a(n) is the least m such that the decimal expansion of n appears in the concatenation of m, ..., m+k for some k >= 0 and Sum_{i = m..m+k-1} A055642(i) < A055642(n) <= Sum_{i = m..m+k} A055642(i).

Original entry on oeis.org

0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 1, 13, 14, 15, 16, 17, 18, 19, 20, 12, 22, 2, 24, 25, 26, 27, 28, 29, 30, 13, 23, 33, 3, 35, 36, 37, 38, 39, 40, 14, 24, 34, 44, 4, 46, 47, 48, 49, 50, 15, 25, 35, 45, 55, 5, 57, 58, 59, 60, 16, 26, 36, 46, 56, 66, 6, 68

Offset: 0

Rémy Sigrist, Jun 22 2021

This sequence is similar to A055642; here we consider decimal expansions, there binary expansions.

			For n = 21:
- the decimal expansion of 21 first appears in the concatenation of 12 and 13,
- so a(21) = 12.

Rémy Sigrist, PARI program for A345672

Cf. A007376, A055642, A083653 (binary analog), A252043.

PARI
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See Links section.
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a(n) <= n.

a(n) = 1 iff n belongs to A252043.

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A083654 Consider the binary Champernowne sequence (A030190): number of successive numbers to be concatenated beginning with A083653(n) such that in binary representation n is contained.

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A083655 Numbers which do not appear prematurely in the binary Champernowne word (A030190).

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A345672 a(n) is the least m such that the decimal expansion of n appears in the concatenation of m, ..., m+k for some k >= 0 and Sum_{i = m..m+k-1} A055642(i) < A055642(n) <= Sum_{i = m..m+k} A055642(i).

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