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 13 results. Next

A027377 Number of irreducible polynomials of degree n over GF(4); dimensions of free Lie algebras.

Original entry on oeis.org

1, 4, 6, 20, 60, 204, 670, 2340, 8160, 29120, 104754, 381300, 1397740, 5162220, 19172790, 71582716, 268431360, 1010580540, 3817733920, 14467258260, 54975528948, 209430785460, 799644629550, 3059510616420
Offset: 0

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Author

Keywords

Comments

Apart from initial terms, exponents in expansion of A065419 as a product zeta(n)^(-a(n)).
Number of aperiodic necklaces with n beads of 4 colors. - Herbert Kociemba, Nov 25 2016

References

  • E. R. Berlekamp, Algebraic Coding Theory, McGraw-Hill, NY, 1968, p. 84.
  • M. Lothaire, Combinatorics on Words. Addison-Wesley, Reading, MA, 1983, p. 79.

Crossrefs

Column k=4 of A074650.

Programs

  • Maple
    A027377 := proc(n) local d,s; if n = 0 then RETURN(1); else s := 0; for d in divisors(n) do s := s+mobius(d)*4^(n/d); od; RETURN(s/n); fi; end;
  • Mathematica
    a[n_] := Sum[MoebiusMu[d]*4^(n/d), {d, Divisors[n]}] / n; a[0] = 1; Table[a[n], {n, 0, 23}](* Jean-François Alcover, Nov 29 2011 *)
    mx=40;f[x_,k_]:=1-Sum[MoebiusMu[i] Log[1-k*x^i]/i,{i,1,mx}];CoefficientList[Series[f[x,4],{x,0,mx}],x] (* Herbert Kociemba, Nov 25 2016 *)
  • PARI
    a(n)=if(n,sumdiv(n,d,moebius(d)<<(2*n/d))/n,1) \\ Charles R Greathouse IV, Nov 29 2011

Formula

a(n) = Sum_{d|n} mu(d)*4^(n/d)/n.
G.f.: k=4, 1 - Sum_{i>=1} mu(i)*log(1 - k*x^i)/i. - Herbert Kociemba, Nov 25 2016
a(n) = A054661(n) + 3 * A054660(n). - Andrey Zabolotskiy, Dec 17 2020
a(n) = 2 * (A054664(n) + A054660(n)). - Andrey Zabolotskiy, Dec 19 2020
a(n) = A054719(n)/n, n>0. - R. J. Mathar, Dec 16 2024

A054661 Number of monic irreducible polynomials over GF(4) with zero trace.

Original entry on oeis.org

1, 0, 5, 12, 51, 160, 585, 2016, 7280, 26112, 95325, 349180, 1290555, 4792320, 17895679, 67104768, 252645135, 954422560, 3616814565, 13743842916, 52357696365, 199911014400, 764877654105, 2932030307680, 11258999068416
Offset: 1

Views

Author

N. J. A. Sloane, Apr 18 2000

Keywords

Comments

Also number of Lyndon words of length n with trace 0 over GF(4).

Crossrefs

Formula

From Andrey Zabolotskiy, Dec 17 2020: (Start)
a(n) = A074031(n) + 3 * A074032(n).
a(n) = A074446(n) + 3 * A074447(n). (End)

Extensions

More terms from James Sellers, Apr 19 2000

A074450 Let x = RootOf(z^2 + z + 1) and y = 1+x. Number of 4-ary Lyndon words of length n over GF(4) with trace 1 and subtrace x.

Original entry on oeis.org

0, 0, 1, 4, 12, 40, 144, 512, 1813, 6528, 23808, 87380, 322560, 1198080, 4473647, 16777216, 63160320, 238605640, 904200192, 3435973836, 13089411609, 49977753600, 191219367936, 733007751680, 2814749599332, 10825959997440, 41699995927744, 160842843834660, 621186153185280
Offset: 1

Views

Author

Frank Ruskey and Nate Kube, Aug 23 2002

Keywords

Comments

Also the number of 4-ary Lyndon words of length n over GF(4) with trace 1 and subtrace y. Also the number of 4-ary Lyndon words of length n over GF(4) with trace x and subtrace 1. Also the number of 4-ary Lyndon words of length n over GF(4) with trace x and subtrace x. Also the number of 4-ary Lyndon words of length n over GF(4) with trace y and subtrace 1. Also the number of 4-ary Lyndon words of length n over GF(4) with trace y and subtrace y.
Is this a duplicate of A074032? - R. J. Mathar, Dec 15 2020

Crossrefs

Extensions

Terms a(16) and beyond from Andrey Zabolotskiy, Jul 21 2021

A074448 Number of 4-ary Lyndon words of length n over GF(4) with trace 1 and subtrace 0.

Original entry on oeis.org

1, 1, 1, 4, 15, 45, 144, 512, 1841, 6579, 23808, 87380, 322875, 1198665, 4473647, 16777216, 63164175, 238612920, 904200192, 3435973836, 13089461538, 49977848925, 191219367936, 733007751680, 2814750270420, 10825961287995, 41699995927744, 160842843834660, 621186162441675
Offset: 1

Views

Author

Frank Ruskey and Nate Kube, Aug 23 2002

Keywords

Comments

Let x = RootOf(z^2 + z + 1) and y = 1 + x. Also the number of 4-ary Lyndon words of length n over GF(4) with trace x and subtrace 0. Also the number of 4-ary Lyndon words of length n over GF(4) with trace y and subtrace 0.

Crossrefs

Extensions

Terms a(16) and beyond from Andrey Zabolotskiy, Jul 21 2021

A074449 Number of 4-ary Lyndon words of length n over GF(4) with trace 1 and subtrace 1.

Original entry on oeis.org

0, 1, 2, 4, 12, 45, 153, 512, 1813, 6579, 23901, 87380, 322560, 1198665, 4474738, 16777216, 63160320, 238612920, 904213989, 3435973836, 13089411609, 49977848925, 191219550297, 733007751680, 2814749599332, 10825961287995, 41699998413248, 160842843834660, 621186153185280
Offset: 1

Views

Author

Frank Ruskey and Nate Kube, Aug 23 2002

Keywords

Comments

Let x = RootOf( z^2+z+1 ) and y = 1+x. Also the number of 4-ary Lyndon words of length n over GF(4) with trace x and subtrace y. Also the number of 4-ary Lyndon words of length n over GF(4) with trace y and subtrace x.

Examples

			Let x = RootOf( z^2+z+1 ) and y = 1+x. a(2; y,x)=1 since the one 4-ary Lyndon word of trace y, subtrace x and length 2 is { 1x }.
		

Crossrefs

Extensions

Terms a(16) and beyond from Andrey Zabolotskiy, Jul 21 2021

A110540 Invertible triangle: T(n,k) = number of k-ary Lyndon words of length n-k+1 with trace 1 modulo k.

Original entry on oeis.org

1, 0, 1, 0, 1, 1, 0, 1, 1, 1, 0, 2, 3, 2, 1, 0, 3, 6, 5, 2, 1, 0, 5, 16, 16, 8, 3, 1, 0, 9, 39, 51, 30, 12, 3, 1, 0, 16, 104, 170, 125, 54, 16, 4, 1, 0, 28, 270, 585, 516, 259, 84, 21, 4, 1, 0, 51, 729, 2048, 2232, 1296, 480, 128, 27, 5, 1, 0, 93, 1960, 7280, 9750, 6665, 2792, 819, 180, 33, 5, 1
Offset: 1

Views

Author

Paul Barry, Jul 25 2005

Keywords

Comments

An invertible number triangle related to Lyndon words of trace 1.

Examples

			Rows begin
  1;
  0,  1;
  0,  1,   1;
  0,  1,   1,    1;
  0,  2,   3,    2,    1;
  0,  3,   6,    5,    2,    1;
  0,  5,  16,   16,    8,    3,   1;
  0,  9,  39,   51,   30,   12,   3,   1;
  0, 16, 104,  170,  125,   54,  16,   4,  1;
  0, 28, 270,  585,  516,  259,  84,  21,  4, 1;
  0, 51, 729, 2048, 2232, 1296, 480, 128, 27, 5, 1;
		

Crossrefs

Programs

  • Mathematica
    T[n_, k_]:=Sum[Boole[GCD[d, k] == 1]  MoebiusMu[d] k^((n - k + 1)/d), {d, Divisors[n - k + 1]}] /(k(n - k + 1)); Flatten[Table[T[n, k], {n, 12}, {k, n}]] (* Indranil Ghosh, Mar 27 2017 *)
  • PARI
    for(n=1, 11, for(k=1, n, print1( sum(d=1,n-k+1, if(Mod(n-k+1, d)==0 && gcd(d, k)==1, moebius(d)*k^((n-k+1)/d), 0)/(k*(n-k+1)) ),", ");); print();) \\ Andrew Howroyd, Mar 26 2017

Formula

T(n, k) = (Sum_{d | n-k+1, gcd(d, k)=1} mu(d)*k^((n-k+1)/d))/(k*(n-k+1)).

Extensions

Name clarified by Andrew Howroyd, Mar 26 2017

A300628 Triangular array T(n,k) giving coefficients in expansion of Product_{j=1..n} (1+x^j)^2 mod x^(n+1)-1.

Original entry on oeis.org

1, 2, 2, 6, 5, 5, 16, 16, 16, 16, 52, 51, 51, 51, 51, 172, 170, 170, 172, 170, 170, 586, 585, 585, 585, 585, 585, 585, 2048, 2048, 2048, 2048, 2048, 2048, 2048, 2048, 7286, 7280, 7280, 7285, 7280, 7280, 7285, 7280, 7280, 26216, 26214, 26214, 26214, 26214, 26216, 26214, 26214, 26214, 26214
Offset: 0

Views

Author

Seiichi Manyama, Mar 10 2018

Keywords

Examples

			Triangle begins:               A053633
  k  0    1    2    3    4   |  k  0    1    2    3    4    5    6    7    8    9
n                            |n
0    1;                      |1    1,   1;
1    2,   2;                 |3    2,   2,   2,   2;
2    6,   5,   5;            |5    6,   5,   5,   6,   5,   5;
3   16,  16,  16,  16;       |7   16,  16,  16,  16,  16,  16,  16,  16;
4   52,  51,  51,  51,  51;  |9   52,  51,  51,  51,  51,  52,  51,  51,  51,  51;
    ...                      |    ...
		

Crossrefs

Programs

  • PARI
    T(n,k) = polcoeff(prod(j=1, n, (1+x^j)^2) % (x^(n+1) - 1), k);
    tabl(nn) = for (n=0, nn, for (k=0, n, print1(T(n, k), ", ")); print); \\ Michel Marcus, Mar 10 2018

A300674 Number of monic irreducible polynomials of degree n over GF(8) that have a given nonzero trace.

Original entry on oeis.org

1, 4, 21, 128, 819, 5460, 37449, 262144, 1864128, 13421772, 97612893, 715827840, 5286113595, 39268272420, 293203100463, 2199023255552, 16557351571215, 125099989647360, 948126237341157, 7205759403792768, 54901024028884989, 419244183493398900, 3208129404123400281, 24595658764945981440
Offset: 1

Views

Author

Seiichi Manyama, Mar 11 2018

Keywords

Crossrefs

Column 8 of A110540.

Programs

  • Mathematica
    a[n_] := DivisorSum[n, MoebiusMu[#] * 8^(n/#) &, OddQ[#] &] / (8*n); Array[a, 24] (* Amiram Eldar, Oct 04 2023 *)
  • PARI
    a(n) = sumdiv(n, d, if (d%2, moebius(d)*8^(n/d)))/(8*n); \\ Michel Marcus, Mar 11 2018

Formula

a(n) = (1/(8*n)) * Sum_{odd d divides n} mu(d)*8^(n/d), where mu is the Möbius function A008683.

A300675 Number of monic irreducible polynomials of degree n over GF(16) that have a given nonzero trace.

Original entry on oeis.org

1, 8, 85, 1024, 13107, 174760, 2396745, 33554432, 477218560, 6871947672, 99955602525, 1466015503360, 21651921285435, 321685687669320, 4803839602524143, 72057594037927936, 1085102592571150095, 16397105843297320960, 248545604361560274405, 3777893186295716170752, 57567896172125197996605
Offset: 1

Views

Author

Seiichi Manyama, Mar 11 2018

Keywords

Crossrefs

Column 16 of A110540.

Programs

  • Mathematica
    a[n_] := DivisorSum[n, MoebiusMu[#] * 16^(n/#) &, OddQ[#] &] / (16*n); Array[a, 21] (* Amiram Eldar, Oct 04 2023 *)
  • PARI
    a(n) = sumdiv(n, d, if (d%2, moebius(d)*16^(n/d)))/(16*n); \\ Michel Marcus, Mar 11 2018

Formula

a(n) = (1/(16*n)) * Sum_{odd d divides n} mu(d)*16^(n/d), where mu is the Möbius function A008683.

A054666 Number of 6-ary Lyndon words with trace 1 mod 6.

Original entry on oeis.org

1, 3, 12, 54, 259, 1296, 6665, 34992, 186624, 1007769, 5496925, 30233088, 167444795, 932906715, 5224277604, 29386561536, 165947641615, 940369969152, 5345260877285, 30467987000514, 174102782860140, 997134120017175
Offset: 1

Views

Author

N. J. A. Sloane, Apr 18 2000

Keywords

Comments

Also number of 6-ary Lyndon words with trace 5 mod 6.

Crossrefs

Extensions

More terms from James Sellers, Apr 19 2000
Showing 1-10 of 13 results. Next