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 1-3 of 3 results.

A005864 The coding-theoretic function A(n,4).

Original entry on oeis.org

1, 1, 1, 2, 2, 4, 8, 16, 20, 40, 72, 144, 256, 512, 1024, 2048
Offset: 1

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Keywords

Comments

Since A(n,3) = A(n+1,4), A(n,3) gives essentially the same sequence.
The next term a(17) is in the range 2816-3276.
Let T_n be the set of SDS-maps of sequential dynamical systems defined over the complete graph K_n in which all vertices have the same vertex function (defined using a set of two possible vertex states). Then a(n) is the maximum number of period-2 orbits that a function in T_n can have. - Colin Defant, Sep 15 2015
Since the n-halved cube graph is isomorphic to (or, if you prefer, defined as) the graph with binary sequences of length n-1 as nodes and edges between pairs of sequences that differ in at most two positions, the independence number of the n-halved cube graph is A(n-1,3) = a(n). - Pontus von Brömssen, Dec 12 2018
a(2^k) = A(2^k-1, 3) = 2^(2^k-k-1) because the hypercube Q(2^k-1) can be perfectly packed with radius-1 spheres, corresponding to a Hamming(2^k-1, 2^k-k-1) code. - Yifan Xie, May 06 2025

References

  • J. H. Conway and N. J. A. Sloane, "Sphere Packings, Lattices and Groups", Springer-Verlag, p. 248.
  • F. J. MacWilliams and N. J. A. Sloane, The Theory of Error-Correcting Codes, Elsevier-North Holland, 1978, p. 674.
  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Cf. A005865: A(n,6) ~ A(n,5), A005866: A(n,8) ~ A(n,7).
Cf. A001839: A(n,4,3), A001843: A(n,4,4), A169763: A(n,4,5).

A005866 The coding-theoretic function A(n,8).

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 4, 4, 8, 16, 32, 36, 64, 128, 256, 512, 1024, 2048, 4096
Offset: 1

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Keywords

Comments

Since A(n,7) = A(n+1,8), A(n,7) gives essentially the same sequence.
The next term, A(25,8), is known to be at least 4096 and at most 5421. - Moshe Milshtein, Dec 03 2018

References

  • J. H. Conway and N. J. A. Sloane, "Sphere Packings, Lattices and Groups", Springer-Verlag, p. 248.
  • F. J. MacWilliams and N. J. A. Sloane, The Theory of Error-Correcting Codes, Elsevier/North Holland, 1978, p. 674.
  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Cf. A005864: A(n,4) and A(n,3), A005865: A(n,6) and A(n,5).
Cf. A005851: A(n,8,5), A005852: A(n,8,6), A005853: A(n,8,7), A004043: A(n,8,8).

Extensions

a(18)-a(24) from Moshe Milshtein, Dec 03 2018

A169761 Consider binary linear [N,K,D] codes with D=6 and redundancy R = N-K = n; a(n) = maximal value of N.

Original entry on oeis.org

6, 7, 9, 12, 18, 24, 34
Offset: 5

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Author

N. J. A. Sloane, May 08 2010

Keywords

Comments

A binary linear [N,K,D] code has length N, dimension K and minimal distance D.

Examples

			a(9) = 18 corresponds to the [18,9,6] extended quadratic residue code.
		

References

  • A. E. Brouwer, J. B. Shearer, N. J. A. Sloane and W. D. Smith, New table of constant weight codes, IEEE Trans. Info. Theory 36 (1990), 1334-1380.
  • F. J. MacWilliams and N. J. A. Sloane, The Theory of Error-Correcting Codes, Elsevier-North Holland, 1978.

Crossrefs

Showing 1-3 of 3 results.