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 51-54 of 54 results.

A136834 Number of dimer arrangements on (2n-1) X (2n-1) square with exactly one monomer.

Original entry on oeis.org

1, 18, 2180, 2200776, 20355006224, 1801272981919008, 1560858753560238398528, 13428038397958481723104394368, 1157111379933346772804754279450353920, 1004777133003025735713513459537724394989392384
Offset: 1

Views

Author

Steven Finch, Apr 03 2008

Keywords

References

  • Y. Kong, Packing dimers on (2p+1) X (2q+1) lattices, Phys. Rev. E 73 (2006) 016106

Crossrefs

Cf. A004003.

A139772 Number of linear trimer coverings of a 3n X 3n square.

Original entry on oeis.org

2, 64, 37160, 378875648, 67433401509980, 209087783283413477232, 11281654633785546173131745084
Offset: 1

Views

Author

Steven Finch, May 20 2008

Keywords

References

  • J. Van Craen, The residual entropy of rectilinear trimers on the square lattice at close packing, J. Chem. Phys. 63 (1975) 2591-2596.

Crossrefs

Cf. A004003.

Extensions

Name corrected and a(6)-a(7) from Andrew Howroyd, Feb 16 2022

A316535 Number of domino tilings (or dimer coverings) of a 2n X 2n square not counting reflections and rotations.

Original entry on oeis.org

1, 1, 9, 930, 1629189, 32324350352, 6632560613086062, 14025276099356126574624, 305611096281378760240051639364, 68617947901923542714137396006469280000, 158748001407029479280360099562172057138013219144, 3784212561528950376893775523091796640110288722110632534528
Offset: 0

Views

Author

Steven Lord, Jul 06 2018

Keywords

Comments

This is the sequence A004003 after removing rotations and reflections. The corresponding terms of A004003 are: 1, 2, 36, 6728, ... .

References

Crossrefs

Cf. A004003.

Extensions

a(6)-a(11) from Andrew Howroyd, Jul 17 2018

A361413 Number of ways to tile an n X n square using rectangles with distinct dimensions where all the rectangle edge lengths are prime numbers.

Original entry on oeis.org

0, 1, 1, 0, 1, 0, 1, 0, 0, 4128, 1, 10880, 641, 45904, 349496, 892088, 40873, 17695080
Offset: 1

Views

Author

Scott R. Shannon, Mar 10 2023

Keywords

Comments

All possible tilings are counted, including those identical by symmetry. Note that distinct dimensions means that, for example, a 2 X 3 rectangle can only be used once, regardless of whether it lies horizontally or vertically.

Examples

			a(2), a(3), a(5), a(7), a(11) = 1 as the only possible tiling is that using an n X n square where n is a prime number. It is likely 11 is the last prime indexed term that equals 1 although this is unknown.
a(10) = 4128. And example tiling is:
.
  +---+---+---+---+---+---+---+---+---+---+
  |       |           |                   |
  +       +           +                   +
  |       |           |                   |
  +---+---+---+---+---+---+---+---+---+---+
  |           |                           |
  +           +                           +
  |           |                           |
  +           +                           +
  |           |                           |
  +---+---+---+                           +
  |           |                           |
  +           +                           +
  |           |                           |
  +           +---+---+---+---+---+---+---+
  |           |                           |
  +           +                           +
  |           |                           |
  +           +                           +
  |           |                           |
  +---+---+---+---+---+---+---+---+---+---+
.
		

Crossrefs

Previous Showing 51-54 of 54 results.