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 1-10 of 62 results. Next

A319198 Partial sums of the infinite self-similar tribonacci word, written in the form A080843.

Original entry on oeis.org

0, 1, 1, 3, 3, 4, 4, 4, 5, 5, 7, 7, 8, 8, 9, 9, 11, 11, 12, 12, 12, 13, 13, 15, 15, 16, 16, 18, 18, 19, 19, 19, 20, 20, 22, 22, 23, 23, 24, 24, 26, 26, 27, 27, 27, 28, 28, 30, 30, 31, 31, 31, 32, 32, 34, 34, 35, 35, 36, 36, 38, 38, 39, 39, 39, 40, 40, 42, 42, 43, 43
Offset: 0

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Author

Wolfdieter Lang, Oct 10 2018

Keywords

Comments

This sequence produces a formula for the A-numbers A278040, specifying the positions (or indices) of 1's in A080843, namely A(n) = 4*n+1 - a(n-1), with a(-1) = 0.

Crossrefs

Cf. A080843, A276797, A276798, A278039 (B-numbers), A278040 (A-numbers), A278041 (C-numbers).

Formula

a(n) = Sum_{j=0..n} A080843(n), n >= 0.
a(n) = z_A(n) + 2*z_C(n) = A276797(n+1) + 2*(A276798(n+1) - 1), where z_A(n) gives the number of A-numbers from A278040 not exceeding n, similarly for z_C(n) with the C-numbers from A278041. - Wolfdieter Lang, Dec 13 2018

A317950 First differences of ternary tribonacci word A080843.

Original entry on oeis.org

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

Views

Author

N. J. A. Sloane, Aug 17 2018

Keywords

Comments

Also first differences of A092782.

Crossrefs

A216190 Abelian complexity function of tribonacci word (A080843).

Original entry on oeis.org

3, 3, 4, 3, 4, 4, 4, 3, 4, 4, 4, 4, 4, 4, 3, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 3, 4, 5, 5, 4, 4, 4, 4, 4, 5, 5, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 3, 4, 4, 5, 4, 5, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 5, 4, 5, 4, 4, 4, 5, 5, 4, 4, 4, 4, 4, 5, 5, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 3, 4, 4, 4
Offset: 1

Views

Author

Nathan Fox, Mar 11 2013

Keywords

Comments

For all n, a(n) equals 3,4,5,6, or 7.
The values 3,4,5,6, and 7 are all obtained infinitely often.
The first 6 occurs when n=342. The first 7 occurs when n=3914.

References

  • G. Richomme, K. Saari, L. Q. Zamboni, Balance and Abelian Complexity of the Tribonacci word, Adv. Appl. Math. 45 (2010) 212-231.

Crossrefs

Cf. A080843.

A345717 Orders of abelian cubes in the tribonacci word A080843.

Original entry on oeis.org

4, 6, 7, 11, 13, 17, 18, 20, 24, 26, 27, 30, 31, 33, 37, 38, 40, 41, 42, 43, 44, 48, 50, 51, 55, 57, 61, 62, 63, 64, 68, 70, 74, 75, 77, 79, 81, 85, 86, 87, 88, 92, 94, 95, 98, 99, 101, 105, 107, 108, 111, 112, 114, 116, 118, 119, 122, 123, 125, 129, 131, 132
Offset: 1

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Author

Jeffrey Shallit, Jun 24 2021

Keywords

Comments

An abelian cube is a word of the form x x' x'', where x' and x'' are permutations of x, like the English word "deeded". The order of an abelian cube is the length of x.

Examples

			Here are the earliest-appearing abelian cubes of the first few orders:
n = 4:  2010.0102.0102
n = 6: 102010.010201.010201
n = 7: 0102010.0102010.1020100
n = 11: 02010010201.01020100102.01020100102
		

Crossrefs

Cf. A080843.

Formula

There is a deterministic finite automaton of 1169 states that takes n in its tribonacci representation as input and accepts if and only if there is an abelian cube of order n. It can be obtained with the Walnut theorem-prover.

A347752 Orders of additive cubes in the tribonacci word A080843.

Original entry on oeis.org

3, 4, 6, 7, 10, 11, 13, 14, 16, 17, 18, 20, 21, 23, 24, 26, 27, 30, 31, 33, 34, 37, 38, 40, 41, 42, 43, 44, 45, 47, 48, 50, 51, 54, 55, 57, 58, 60, 61, 62, 63, 64, 65, 67, 68, 70, 71, 74, 75, 77, 78, 79, 81, 82, 84, 85, 86, 87, 88, 89, 91, 92, 94, 95, 97, 98, 99
Offset: 1

Views

Author

Jeffrey Shallit, Sep 18 2021

Keywords

Comments

An additive cube is three consecutive blocks of the same length and same sum.
There is a tribonacci automaton of 4927 states recognizing the set of these orders (in tribonacci representation).

Examples

			The first few examples of additive cubes of different lengths in the tribonacci word are 020.101.020 (order 3), 2010.0102.0102 (order 4), and 102010.010201.010201 (order 6)
		

Crossrefs

A275933 Decimal expansion of constant related to complexity of the tribonacci word (A080843).

Original entry on oeis.org

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

Views

Author

N. J. A. Sloane, Sep 02 2016

Keywords

Comments

The minimal polynomial of this constant is x^3 - 13*x^2 + 27*x - 17, and it is its unique real root. - Amiram Eldar, May 27 2023

Examples

			10.6052382910266361207972696375...
		

Crossrefs

Programs

  • Mathematica
    RealDigits[x /. FindRoot[x^3 - 13*x^2 + 27*x - 17, {x, 10}, WorkingPrecision -> 120]][[1]] (* Amiram Eldar, May 27 2023 *)

Formula

Equals 9+(6*t-4)/(t^2+1), where t is the tribonacci constant A058265.
Equals (13 + (847 - 33*sqrt(33))^(1/3) + (11 * (77 + 3*sqrt(33)))^(1/3))/3. - Amiram Eldar, May 27 2023

Extensions

More terms from Joerg Arndt, Sep 02 2016

A308525 Quasiperiods of the ternary tribonacci sequence (A080843).

Original entry on oeis.org

7, 13, 14, 24, 25, 26, 27, 44, 45, 46, 47, 48, 49, 50, 51, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 149, 150, 151, 152, 153, 154, 155, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, 167, 168, 169, 170, 171, 172, 173, 174, 175, 176
Offset: 1

Views

Author

Jeffrey Shallit, Jun 11 2019

Keywords

Comments

A word x is a quasiperiod of another (possibly infinite) word w if you can cover all of the symbols of w by translates of x.

Crossrefs

Cf. A080843.

A308627 Numbers k such that the ternary tribonacci sequence (A080843) has a Lyndon factor of length k.

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 7, 9, 11, 13, 16, 18, 20, 22, 24, 29, 31, 35, 37, 40, 42, 44, 53, 55, 57, 64, 66, 68, 77, 79, 81, 97, 99, 101, 110, 112, 121, 123, 125, 134, 136, 145, 147, 149, 178, 180, 189, 191, 193, 215, 217, 226, 228, 230, 246, 248, 250, 259, 261, 270
Offset: 1

Views

Author

Jeffrey Shallit, Jun 11 2019

Keywords

Comments

A "factor" is a contiguous subblock. A factor is "Lyndon" if it is lexicographically least among all its cyclic shifts.

Crossrefs

Cf. A080843.

A345733 Numbers k such that there are two distinct abelian squares of order k in the tribonacci word A080843.

Original entry on oeis.org

15, 34, 59, 90, 96, 97, 102, 134, 137, 170, 171, 172, 178, 183, 215, 240, 252, 259, 262, 289, 321, 333, 364, 370, 371, 387, 389, 391, 402, 408, 411, 445, 457, 470, 482, 489, 516, 519, 538, 556, 557, 563, 594, 600, 601, 606, 638, 665, 674, 675, 676, 682, 687
Offset: 1

Views

Author

Jeffrey Shallit, Jun 25 2021

Keywords

Comments

An abelian square is a word of the form x x' where x' is a permutation of x, like the English word "reappear". The order of an abelian square x x' is the length of x.
The tribonacci word has abelian squares of all orders. If we consider two abelian squares x x' and y y' to be the same if y is a permutation of x, then some orders have only 1 abelian square (up to this equivalence), while others have 2, and these are the only possibilities. There is a 463-state automaton that recognizes the tribonacci representation of those terms k in this sequence. All this can be proved with the Walnut theorem prover.

Examples

			For k = 15, the two distinct abelian squares are 100102010102010.010201001020101 and 020102010010201.010201001020102.
		

Crossrefs

Cf. A080843.

A345901 a(n) is the largest k such that the tribonacci word A080843 contains a block of length k*n that is an abelian k-th power.

Original entry on oeis.org

2, 2, 2, 3, 2, 4, 5, 2, 2, 2, 4, 2, 8, 2, 2, 2, 4, 3, 2, 6, 2, 2, 2, 8, 2, 4, 3, 2, 2, 3, 6, 2, 3, 2, 2, 2, 10, 3, 2, 3, 3, 3, 3, 13, 2, 2, 2, 4, 2, 5, 4, 2, 2, 2, 5, 2, 6, 2, 2, 2, 6, 3, 3, 4, 2, 2, 2, 12, 2, 3, 2, 2, 2, 5, 5, 2, 3, 2, 3, 2, 21, 2, 2, 2, 4, 3
Offset: 1

Views

Author

Jeffrey Shallit, Jun 29 2021

Keywords

Comments

An abelian k-th power consists of k blocks x_1 x_2 ... x_k such that each x_i is a permutation of x_1. For example, the English word "deeded" is an abelian 3rd power.

Examples

			For n=4, A080843 contains the block 2010.0102.0102, which is an abelian 3rd power. But no blocks of size 16 in A080843 are abelian 4th powers.
		

Crossrefs

Cf. A080843.
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