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 1-9 of 9 results.

A105675 Highest minimal distance of any Type II doubly-even binary self-dual code of length 8n.

Original entry on oeis.org

4, 4, 8, 8, 8, 12, 12, 12
Offset: 1

Views

Author

N. J. A. Sloane, May 06 2005

Keywords

Comments

Is a(9) = 12 or 16? This is an open question of long standing.

Examples

			At length 8 the only Type II doubly-even self-dual code is the Hamming code e_8, which has d=4, so a(1) = 4. The [24,12,8] Golay code has d=8, so a(3) = 8.
		

References

  • F. J. MacWilliams and N. J. A. Sloane, The Theory of Error-Correcting Codes, Elsevier/North Holland, 1977.

Crossrefs

A034414 Leading term in extremal weight enumerator of doubly-even binary self-dual code of length 24n.

Original entry on oeis.org

1, 759, 17296, 249849, 3217056, 39703755, 481008528, 5776211364, 69065734464, 824142912363, 9826364199840, 117145945726810, 1396918583188128, 16665451879695801, 198937019774252928
Offset: 0

Views

Author

Keywords

Comments

The term after the leading nonzero term eventually becomes negative and so for large n the extremal codes do not exist (see references, also A034415).

Examples

			At length 24, the extremal weight enumerator is 1+759*x^8+2576*x^12+..., with leading coefficient 759; this is the weight enumerator of the binary Golay code.
		

References

  • F. J. MacWilliams and N. J. A. Sloane, The Theory of Error-Correcting Codes, Elsevier-North Holland, 1978, see Theorem 13, p. 624.
  • C. L. Mallows and N. J. A. Sloane, An Upper Bound for Self-Dual Codes, Information and Control, 22 (1973), 188-200.

Crossrefs

Cf. A034415 (second coefficient, which becmes negative), A001380, A034597.

Programs

  • Maple
    # Extremal weight enumerators:
    kernelopts(printbytes=false): interface(screenwidth=200);
    W0:=1; f:=1+14*x+x^2; f:=f^3; g:=x*(1-x)^4;
    for mu from 1 to 100 do
    # set max deg
    md:=mu+3; W0:=series(f^mu,x,md): h:=series(g/f,x,md): A:=series(W0,x,md): Z:=A:
    for i from 1 to mu do
    Z:=series(Z*h,x,md); A:=series(A-coeff(A,x,i)*Z,x,md); od: lprint(A);
    od:
  • Mathematica
    a[n_] := 18(6n-1)(8n-1)(12n-1)(24n-1)Binomial[5n-2, n-1]/((n+1)(2n+1)(4n+1)(4n+3)); a[0] = 1; Table[a[n], {n, 0, 14}](* Jean-François Alcover, Oct 06 2011, after formula *)

Formula

a(24n) = C(24n, 5)*C(5n-2, n-1)/C(4n+4, 5).

A034415 Second term in extremal weight enumerator of doubly-even binary self-dual code of length 24n.

Original entry on oeis.org

1, 2576, 535095, 18106704, 369844880, 6101289120, 90184804281, 1251098739072, 16681003659936, 216644275600560, 2763033644875595, 34784314216176096, 433742858109499536, 5369839142579042560
Offset: 0

Views

Author

Keywords

Comments

The terms become negative at n=154 and so certainly by that point the extremal codes do not exist (see references).
Up to n = 250 the terms steadily increase in magnitude, but their sign changes from positive to negative at n = 154.

Examples

			At length 24, the weight enumerator (of the Golay code) is 1+759*x^8+2576*x^12+..., with leading coefficient 759 and second term 2576.
		

References

  • F. J. MacWilliams and N. J. A. Sloane, The Theory of Error-Correcting Codes, Elsevier-North Holland, 1978, see Theorem 13, p. 624.

Crossrefs

Cf. A034414 (leading coefficient), A001380, A034597, A034598.

Programs

  • Maple
    For Maple program see A034414.

A002289 Weight distribution of [ 23,12,7 ] binary perfect Golay code.

Original entry on oeis.org

1, 0, 0, 0, 0, 0, 0, 253, 506, 0, 0, 1288, 1288, 0, 0, 506, 253, 0, 0, 0, 0, 0, 0, 1
Offset: 0

Views

Author

Keywords

References

  • W. Ebeling, Lattices and Codes, Vieweg; 2nd ed., 2002, see p. 71.
  • F. J. MacWilliams and N. J. A. Sloane, The Theory of Error-Correcting Codes, Elsevier-North Holland, 1978, p. 635.

Crossrefs

Cf. A001380.

A105683 Weight distribution of [12,6,6]_3 ternary extended Golay code.

Original entry on oeis.org

1, 0, 264, 440, 24
Offset: 0

Views

Author

N. J. A. Sloane, May 06 2005

Keywords

Examples

			Weight enumerator is x^12 + 264*x^6*y^6 + 440*x^3*y^9 + 24*y^12.
		

References

  • J. H. Conway and N. J. A. Sloane, "Sphere Packings, Lattices and Groups", Springer-Verlag.
  • F. J. MacWilliams and N. J. A. Sloane, The Theory of Error-Correcting Codes, Elsevier/North Holland, 1977.

Crossrefs

Programs

  • Magma
    K:=FiniteField(3); C:=GolayCode(K,true); W:=WeightEnumerator(C); W;

A122192 Sum of the n-th powers of the roots of the (reduced) weight enumerator of the extended Golay code (1 + 759*x^2 + 2576*x^3 + 759*x^4 + x^6).

Original entry on oeis.org

6, 0, -1518, -7728, 1149126, 9775920, -851127150, -10374206304, 619950551814, 10059106207584, -443172509029998, -9223980220220304, 309985135145332422, 8134978519171135632, -211181377213616588526, -6965969413257227260608, 139095682365347347024902
Offset: 0

Views

Author

N. J. A. Sloane, Nov 12 2006

Keywords

Crossrefs

Programs

  • Maple
    Newt:=proc(f) local t1,t2,t3,t4; t1:=f; t2:=diff(f,x); t3:=expand(x^degree(t1,x)*subs(x=1/x,t1)); t4:=expand(x^degree(t2,x)*subs(x=1/x,t2)); factor(t4/t3); end;
    g:=1+759*x^2+2576*x^3+759*x^4+x^6; Newt(g); series(%,x,60);
  • Mathematica
    LinearRecurrence[{0,-759,-2576,-759,0,-1}, {6,0,-1518,-7728,1149126,9775920}, 30] (* G. C. Greubel, Jul 11 2021 *)
  • PARI
    polsym(x^6 + 759*x^4 + 2576*x^3 + 759*x^2 + 1, 30) \\ Charles R Greathouse IV, Jul 20 2016
    
  • Sage
    def A122192_list(prec):
        P. = PowerSeriesRing(ZZ, prec)
        return P( 6*(1+506*x^2+1288*x^3+253*x^4)/(1+759*x^2+2576*x^3+759*x^4 +x^6) ).list()
    A122192_list(30) # G. C. Greubel, Jul 11 2021

Formula

G.f.: 6*(1 + 506*x^2 + 1288*x^3 + 253*x^4)/(1 + 759*x^2 + 2576*x^3 + 759*x^4 + x^6).

A018235 Weight distribution of (48,2^24,12) binary code obtained from Golay code of length 24 lifted to Z/4Z and mapped to GF(2)^2.

Original entry on oeis.org

1, 0, 0, 0, 0, 0, 12144, 61824, 195063, 1133440, 1445136, 4080384, 2921232, 4080384, 1445136, 1133440, 195063, 61824, 12144, 0, 0, 0, 0, 0, 1
Offset: 0

Views

Author

Keywords

References

  • K. Tanabe, A criterion for designs in Z_4-codes on the symmetrized weight enumerator, Des. Codes Cryptogr. 30 (2003), 169-185.

Crossrefs

A105547 Hamming weight distribution of code obtained by lifting Golay code of length 24 to Z/4Z.

Original entry on oeis.org

1, 0, 0, 0, 0, 0, 0, 0, 759, 0, 12144, 0, 172592, 61824, 765072, 1133440, 1239447, 4080384, 1445136, 4080384, 1870176, 1133440, 692208, 61824, 28385
Offset: 0

Views

Author

N. J. A. Sloane, May 07 2005

Keywords

References

  • S. T. Dougherty, S. Y. Kim and Y. H. Park, Lifted codes and their weight enumerators, Discrete Math., 305 (2005), 123-135.
  • K. Tanabe, A criterion for designs in Z_4-codes on the symmetrized weight enumerator, Des. Codes Cryptogr. 30 (2003), 169-185.

Crossrefs

A105684 Weight distribution of [11,6,5]_3 ternary Golay perfect code.

Original entry on oeis.org

1, 0, 0, 0, 0, 132, 132, 0, 330, 110, 0, 24
Offset: 0

Views

Author

N. J. A. Sloane, May 06 2005

Keywords

Examples

			Weight enumerator is x^11 + 132*x^6*y^5 + 132*x^5*y^6 + 330*x^3*y^8 + 110*x^2*y^9 + 24*y^11.
		

References

  • J. H. Conway and N. J. A. Sloane, "Sphere Packings, Lattices and Groups", Springer-Verlag.
  • F. J. MacWilliams and N. J. A. Sloane, The Theory of Error-Correcting Codes, Elsevier/North Holland, 1977.

Crossrefs

Programs

  • Magma
    K:=FiniteField(3); C:=GolayCode(K,false); W:=WeightEnumerator(C); W;
Showing 1-9 of 9 results.