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 1-4 of 4 results.

A004026 Number of perfect quadratic forms or lattices in dimension n.

Original entry on oeis.org

1, 1, 1, 2, 3, 7, 33, 10916
Offset: 1

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Author

Keywords

References

  • D.-O. Jaquet, Classification des réseaux dans R^7 (via la notion de formes parfaites), Journées Arithmétiques, 1989 (Luminy, 1989). Asterisque No. 198-200 (1991), 7-8, 177-185 (1992).
  • J. Martinet, Les réseaux parfaits des espaces Euclidiens, Masson, Paris, 1996, p. 175.
  • J. Martinet, Perfect Lattices in Euclidean Spaces, Springer-Verlag, NY, 2003.
  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
  • A. Schürmann, Enumerating perfect forms, Contemporary Math., 493 (2009), 359-377. [From N. J. A. Sloane, Jan 21 2010]

Crossrefs

Extensions

a(8) from the work of Mathieu Dutour Sikiric, Achill Schuermann and Frank Vallentin, Oct 05 2005

A037075 Number of eutactic lattices in dimension n.

Original entry on oeis.org

1, 2, 5, 16, 118
Offset: 1

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Author

J. Martinet (martinet(AT)math.u-bordeaux.fr), N. J. A. Sloane

Keywords

References

  • J. Martinet, Les réseaux parfaits des espaces Euclidiens, Masson, Paris, 1996.
  • J. Martinet, Perfect Lattices in Euclidean Spaces, Springer-Verlag, NY, 2003.
  • G. Nebe, Review of J. Martinet, Perfect Lattices in Euclidean Spaces, Bull. Amer. Math. Soc., 41 (No. 4, 2004), 529-533.

Crossrefs

A065535 Number of strongly perfect lattices in dimension n.

Original entry on oeis.org

1, 1, 0, 1, 0, 1, 1, 1, 0, 1, 0
Offset: 1

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Author

N. J. A. Sloane, Nov 16 2001

Keywords

Comments

It is known that a(12) through a(24) are at least 1, 0, 1, 0, 3, 0, 1, 0, 1, 1, 5, 4, 2 respectively.
In this sequence, the dual pairs of lattices are counted as one if they are both strongly perfect (it is not always so). E.g., in dimensions 6, 7, 10 there are two strongly perfect lattices, forming a dual pair, but in dimension 21 there is a strongly perfect lattice which has a not strongly perfect dual. - Andrey Zabolotskiy, Feb 20 2021

References

  • J. Martinet, Les réseaux parfaits des espaces euclidiens, Masson, Paris, 1996.
  • J. Martinet, Perfect Lattices in Euclidean Spaces, Springer-Verlag, NY, 2003. See Section 16.2.

Crossrefs

A097584 Number of well-rounded minimal classes of lattices in dimension n.

Original entry on oeis.org

1, 2, 5, 18, 136, 5634
Offset: 1

Views

Author

N. J. A. Sloane, Sep 22 2004

Keywords

References

  • J. Martinet, Les réseaux parfaits des espaces Euclidiens, Masson, Paris, 1996.
  • J. Martinet, Perfect Lattices in Euclidean Spaces, Springer-Verlag, NY, 2003.
  • G. Nebe, Review of J. Martinet, Perfect Lattices in Euclidean Spaces, Bull. Amer. Math. Soc., 41 (No. 4, 2004), 529-533.

Crossrefs

Extensions

a(6) added from Batut & Martinet by Andrey Zabolotskiy, Feb 20 2021
Showing 1-4 of 4 results.