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 1-6 of 6 results.

A079137 Number of (undirected) Hamiltonian paths on the 4 X n knight graph.

Original entry on oeis.org

0, 0, 8, 0, 82, 744, 6378, 31088, 189688, 1213112, 6683852, 36486328, 201282470, 1083585304, 5706117458, 29819231288, 154430502724, 790787799376, 4014945695196, 20241304810488, 101336136490228, 504096313001272, 2493533648002492, 12270473056485396
Offset: 1

Views

Author

Eric W. Weisstein, Dec 28 2002

Keywords

References

  • Kraitchik, M. Mathematical Recreations. New York: W. W. Norton, p. 263, 1942.

Crossrefs

See A079312 for 4 times these numbers, A123935 for twice these numbers, A123936 for these numbers halved.

Extensions

More terms from André Pönitz (poenitz(AT)htwm.de), Jun 11 2003
Edited by N. J. A. Sloane, Oct 30 2006, following suggestions from Colin Rose
Terms a(22) and beyond from Andrew Howroyd, Jul 01 2017

A001230 Number of undirected closed knight's tours on a 2n X 2n chessboard.

Original entry on oeis.org

0, 0, 9862, 13267364410532
Offset: 1

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Author

N. J. A. Sloane, Martin Loebbing (loebbing(AT)ls2.informatik.uni-dortmund.de), Brendan McKay

Keywords

Comments

No closed tour exists on an m X m board if m is odd.

References

  • Brendan McKay, personal communication, Feb 03, 1997.
  • W. W. Rouse Ball, Mathematical Recreations and Essays (various editions), Chap. 6.
  • I. Wegener, Branching Programs and Binary Decision Diagrams, SIAM, Philadelphia, 2000; see p. 369.

Crossrefs

Cf. A165134.

Programs

  • Mathematica
    Table[Length[FindHamiltonianCycle[KnightTourGraph[2 n, 2 n], All]], {n, 3}]

Extensions

Loebbing and Wegener incorrectly gave 33439123484294 for the 8 X 8 board. The value given here is due to Brendan McKay and agrees with that given by Wegener in his book.
Description and links corrected by Max Alekseyev, Dec 09 2008

A118067 Number of (directed) Hamiltonian paths in the 3 X n knight graph.

Original entry on oeis.org

0, 0, 0, 16, 0, 0, 104, 792, 1120, 6096, 21344, 114496, 257728, 1292544, 3677568, 17273760, 46801984, 211731376, 611507360, 2645699504, 7725948608, 32451640000, 97488160384, 397346625760, 1214082434112, 4835168968464, 15039729265856, 58641619298000
Offset: 1

Views

Author

Colin Rose, May 11 2006

Keywords

Comments

1. Jelliss computes the number of tour diagrams (which is equal to half the number of tours). 2. Sequence A079137 computes the number of tour DIAGRAMS for a 4 X k board (again, equal to half the number of tours). 3. Kraitchik (1942) incorrectly reports 376 tour diagrams for the 3 X 8 case; the correct number is 396 (i.e., 792 tours) [cf. Rose, Jelliss].

References

  • Kraitchik, M., Mathematical Recreations. New York: W. W. Norton, pp. 264-5, 1942.

Crossrefs

Programs

  • Mathematica
    Mathematica notebook available at: http://www.tri.org.au/knightframe.html

Formula

a(n) = 2 * A169696(n). - Andrew Howroyd, Jul 01 2017

Extensions

a(13) from Eric W. Weisstein, Mar 13 2009
a(14)-a(21) from Seiichi Manyama, Apr 25 2016
a(22)-a(28) from Andrew Howroyd, Jul 01 2017

A306282 Triangle read by rows: T(n,k) is the number of (directed) Hamiltonian paths in the n X k knight graph.

Original entry on oeis.org

1, 0, 0, 0, 0, 0, 0, 0, 16, 0, 0, 0, 0, 164, 1728, 0, 0, 0, 1488, 37568, 6637920, 0, 0, 104, 12756, 1245736, 779938932, 165575218320, 0, 0, 792, 62176, 36122108
Offset: 1

Views

Author

Seiichi Manyama, Feb 03 2019

Keywords

Examples

			Triangle begins:
n\k | 1  2    3      4        5          6             7
----+----------------------------------------------------
1   | 1;
2   | 0, 0;
3   | 0, 0,   0;
4   | 0, 0,  16,     0;
5   | 0, 0,   0,   164,    1728;
6   | 0, 0,   0,  1488,   37568,   6637920;
7   | 0, 0, 104, 12756, 1245736, 779938932, 165575218320;
		

Crossrefs

T(n,n) gives A165134.

A308131 Number of (undirected) Hamiltonian paths in the n X n knight graph.

Original entry on oeis.org

0, 0, 0, 0, 864, 3318960, 82787609160, 9795914085489952
Offset: 1

Views

Author

Eric W. Weisstein, May 14 2019

Keywords

Crossrefs

Cf. A165134, A169696 (3 X n), A079137 (4 X n), A083386 (5 X n), A306281 (6 X n), A306283 (7 X n).

Formula

a(n) = A165134(n)/2.

A289204 Number of (undirected) paths in the n X n knight graph.

Original entry on oeis.org

0, 0, 56, 14980, 19005336, 278982789260
Offset: 1

Views

Author

Eric W. Weisstein, Jun 28 2017

Keywords

Crossrefs

Extensions

a(5)-a(6) from Andrew Howroyd, Jul 01 2017
Showing 1-6 of 6 results.