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.

Previous Showing 41-50 of 55 results. Next

A060221 Number of orbits of length n under the full 18-shift (whose periodic points are counted by A001027).

Original entry on oeis.org

18, 153, 1938, 26163, 377910, 5667681, 87460002, 1377481950, 22039920504, 357046533675, 5842582734474, 96402612275775, 1601766528128550, 26772383354990049, 449776041098370870, 7589970692848393200, 128583032925805678350, 2185911559727674682148, 37275544492386193492506
Offset: 1

Views

Author

Thomas Ward, Mar 21 2001

Keywords

Comments

Number of Lyndon words (aperiodic necklaces) with n beads of 18 colors. - Andrew Howroyd, Dec 10 2017

Examples

			a(2)=153 since there are 324 points of period 2 in the full 18-shift and 18 fixed points, so there must be (324-18)/2 = 153 orbits of length 2.
		

Crossrefs

Column 18 of A074650.

Programs

  • Magma
    A060221:= func< n | (1/n)*(&+[MoebiusMu(d)*(18)^Floor(n/d): d in Divisors(n)]) >;
    [A060221(n): n in [1..40]]; // G. C. Greubel, Sep 13 2024
    
  • Mathematica
    A060221[n_]:= DivisorSum[n, (18)^(n/#)*MoebiusMu[#] &]/n;
    Table[A060221[n], {n, 40}] (* G. C. Greubel, Sep 13 2024 *)
  • PARI
    a001027(n) = 18^n;
    a(n) = (1/n)*sumdiv(n, d, moebius(d)*a001027(n/d)); \\ Michel Marcus, Sep 11 2017
    
  • SageMath
    def A060221(n): return (1/n)*sum(moebius(k)*(18)^(n/k) for k in (1..n) if (k).divides(n))
    [A060221(n) for n in range(1,41)] # G. C. Greubel, Sep 13 2024

Formula

a(n) = (1/n)* Sum_{d|n} mu(d)*A001027(n/d).
G.f.: Sum_{k>=1} mu(k)*log(1/(1 - 18*x^k))/k. - Ilya Gutkovskiy, May 20 2019

Extensions

More terms from Michel Marcus, Sep 11 2017

A060222 Number of orbits of length n under the full 19-shift (whose periodic points are counted by A001029).

Original entry on oeis.org

19, 171, 2280, 32490, 495216, 7839780, 127695960, 2122929090, 35854187880, 613106378136, 10590023536200, 184442905990860, 3234844881712080, 57071906063500860, 1012075135324821024, 18027588346914850290, 322375697516753069760, 5784852794310472599780, 104127350297911241532840
Offset: 1

Views

Author

Thomas Ward, Mar 21 2001

Keywords

Comments

Number of monic irreducible polynomials of degree n over GF(19). - Andrew Howroyd, Dec 10 2017

Examples

			a(2)=171 since there are 361 points of period 2 in the full 19-shift and 19 fixed points, so there must be (361-19)/2 = 171 orbits of length 2.
		

Crossrefs

Column 19 of A074650.
Cf. A001029.

Programs

  • Magma
    A060222:= func< n | (1/n)*(&+[MoebiusMu(d)*(19)^Floor(n/d): d in Divisors(n)]) >;
    [A060222(n): n in [1..40]]; // G. C. Greubel, Sep 23 2024
    
  • Mathematica
    a[n_]:=(1/n) Sum[MoebiusMu[d] 19^(n/d), {d, Divisors[n]}]; Table[a[n], {n, 20}] (* Vincenzo Librandi, Sep 19 2017 *)
  • PARI
    a001029(n) = 19^n;
    a(n) = (1/n)*sumdiv(n, d, moebius(d)*a001029(n/d)); \\ Michel Marcus, Sep 11 2017
    
  • SageMath
    def A060222(n): return (1/n)*sum(moebius(k)*(19)^(n/k) for k in (1..n) if (k).divides(n))
    [A060222(n) for n in range(1, 41)] # G. C. Greubel, Sep 23 2024

Formula

a(n) = (1/n)* Sum_{d|n} mu(d)*A001029(n/d).
G.f.: Sum_{k>=1} mu(k)*log(1/(1 - 19*x^k))/k. - Ilya Gutkovskiy, May 20 2019

Extensions

More terms from Michel Marcus, Sep 11 2017

A292350 Number of Lyndon words (aperiodic necklaces) with 6 beads of n colors.

Original entry on oeis.org

0, 9, 116, 670, 2580, 7735, 19544, 43596, 88440, 166485, 295020, 497354, 804076, 1254435, 1897840, 2795480, 4022064, 5667681, 7839780, 10665270, 14292740, 18894799, 24670536, 31848100, 40687400, 51482925, 64566684, 80311266, 99133020, 121495355, 147912160
Offset: 1

Views

Author

Eric M. Schmidt, Dec 08 2017

Keywords

Crossrefs

Row n=6 of A074650.

Programs

  • PARI
    concat(0, Vec(x^2*(9 + 53*x + 47*x^2 + 11*x^3) / (1 - x)^7 + O(x^40))) \\ Colin Barker, Dec 08 2017

Formula

a(n) = (n^6 - n^3 - n^2 + n)/6.
From Colin Barker, Dec 08 2017: (Start)
G.f.: x^2*(9 + 53*x + 47*x^2 + 11*x^3) / (1 - x)^7.
a(n) = 7*a(n-1) - 21*a(n-2) + 35*a(n-3) - 35*a(n-4) + 21*a(n-5) - 7*a(n-6) + a(n-7) for n>7.
(End)

A352745 a(n) is the number of Lyndon factors of the Fibonacci string of length n.

Original entry on oeis.org

1, 1, 1, 2, 2, 3, 4, 4, 6, 5, 8, 6, 10, 7, 12, 8, 14, 9, 16, 10, 18, 11, 20, 12, 22, 13, 24, 14, 26, 15, 28, 16, 30, 17, 32, 18, 34, 19, 36, 20, 38, 21, 40, 22, 42, 23, 44
Offset: 0

Views

Author

Peter Luschny, Apr 06 2022

Keywords

Comments

The Fibonacci string of length n is defined Fibonacci(n) = cat(Fibonacci(n - 1), Fibonacci(n - 2)) for 1 < n and the initial conditions Fibonacci(0) = "1" and Fibonacci(1) = "0", where 'cat' is the operation of concatenating strings. The length of Fibonacci(n) is A352744(1, n). The sequence starts: "1", "0", "01", "010", "01001", "01001010", ...
Apart from the first four terms seems to be identical with A117248.

Examples

			The Lyndon factorization of the Fibonacci strings of length n = 0..9.
[0] ["1"]
[1] ["0"]
[2] ["01"]
[3] ["01", "0"]
[4] ["01", "001"]
[5] ["01", "00101", "0"]
[6] ["01", "00101", "001", "001"]
[7] ["01", "00101", "0010010100101", "0"]
[8] ["01", "00101", "0010010100101", "00100101", "001", "001"]
[9] ["01", "00101", "0010010100101", "0010010100100101001010010010100101", "0"]
		

Crossrefs

Programs

  • Maple
    with(StringTools): A352745 := n -> nops(LyndonFactors(Fibonacci(n))):
    seq(A352745(n), n = 0..12);

A352746 a(n) is the number of Lyndon factors of the Thue-Morse string of length n.

Original entry on oeis.org

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

Views

Author

Peter Luschny, Apr 06 2022

Keywords

Comments

The Thue-Morse string of length n is the length-n prefix of the infinite Thue-Morse string. The sequence starts: "", "0", "01", "011", "0110", "01101", "011010", ...

Examples

			The Lyndon factorization of the Thue-Morse strings of length n = 0..9.
[0] []
[1] ["0"]
[2] ["01"]
[3] ["011"]
[4] ["011", "0"]
[5] ["011", "01"]
[6] ["011", "01", "0"]
[7] ["011", "01", "0", "0"]
[8] ["011", "01", "001"]
[9] ["011", "01", "0011"]
		

Crossrefs

Programs

  • Maple
    with(StringTools): A352746 := n -> nops(LyndonFactors(ThueMorse(n))):
    seq(A352746(n), n = 0..12);

A006174 Witt vector *3!.

Original entry on oeis.org

6, 27, 488, 7974, 149796, 2725447, 56970432, 1151053821, 25279412332, 543871341927, 12411512060544, 278163517356594, 6498314231705568, 149846653983570795, 3565206002960088128, 84045618111578025105
Offset: 1

Views

Author

Keywords

Comments

If c is the Witt transform of b then b(n) = Sum_{d|n} A074650(n/d, c(d)).

References

  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Formula

Witt transform of A074651.

Extensions

More terms and formula from Christian G. Bower, Aug 28 2002

A006175 Witt vector *4!.

Original entry on oeis.org

24, 972, 118592, 15210414, 2344956480, 377420590432, 67501965869568, 12329221295657241, 2383082885396731968, 467786496795764717088, 95188347941581635319296, 19578329367376510676884584
Offset: 1

Views

Author

Keywords

Comments

If c is the Witt transform of b then b(n) = Sum_{d|n} A074650(n/d, c(d)).

References

  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Formula

Witt transform of A074652.

Extensions

More terms and formula from Christian G. Bower, Aug 28 2002

A006176 Witt vector *5!.

Original entry on oeis.org

120, 49500, 55480000, 75108093750, 124667171985024, 226899085942554400, 453922674315047424000, 954267187464733528198125, 2112236210012497151219800000, 4825706564405954731805322783552
Offset: 1

Views

Author

Keywords

Comments

If c is the Witt transform of b then b(n) = Sum_{d|n} A074650(n/d, c(d)).

References

  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Formula

Witt transform of A074653.

Extensions

More terms and formula from Christian G. Bower, Aug 28 2002

A006178 Witt vector *3!/3!.

Original entry on oeis.org

1, 7, 93, 1419, 25225, 472037, 9501737, 196190781, 4219610242, 92198459515, 2068590840349, 46897782768404, 1083052539395723, 25199771186287195, 594383312662808405, 14098935496013599680, 337939791145403719897
Offset: 1

Views

Author

Keywords

Comments

If c is the Witt transform of b then b(n) = Sum_{d|n} A074650(n/d, c(d)).

References

  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Formula

Witt transform of A029808.

Extensions

More terms and formula from Christian G. Bower, Aug 28 2002

A006179 Witt vector *4!/4!.

Original entry on oeis.org

1, 52, 5133, 655554, 97772875, 16019720210, 2812609211657, 518332479161091, 99318252448110232, 19600890528520952329, 3966181169996511862429, 818653886943854653597621, 171938262068874336023196923
Offset: 1

Views

Author

Keywords

Comments

If c is the Witt transform of b then b(n) = Sum_{d|n} A074650(n/d, c(d)).

References

  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Formula

Witt transform of A029809.

Extensions

More terms and formula from Christian G. Bower, Aug 28 2002
Previous Showing 41-50 of 55 results. Next