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 1-5 of 5 results.

A323559 Number of rooted self-avoiding knight's paths of length n on an infinite chessboard with first move specified.

Original entry on oeis.org

1, 7, 49, 337, 2323, 15805, 107737, 727619, 4921655, 33056939, 222323989, 1487064391, 9957971965, 66391431607, 443085643919, 2946553003837, 19611967535129, 130149475953673
Offset: 1

Views

Author

Hugo Pfoertner, Jan 17 2019

Keywords

Crossrefs

A376736 a(n) is the numerator of the expected number of random moves of a chess knight to reach a position outside an nXn chessboard, starting in one of the corners.

Original entry on oeis.org

1, 1, 4, 62, 269, 1766, 395497, 101338, 44125237, 227721959, 3361699348115, 483866477194862, 277887411827604127, 790848403160840410, 2785714552717079970073201, 89715505143567836216964174, 2034961072108249587083318018747, 457177774768288408431166142758841, 1085703228381446052419019696184520372520
Offset: 1

Views

Author

Hugo Pfoertner, Oct 03 2024

Keywords

Comments

The piece does not pay attention to its position and will fall off the board if it makes a move beyond the edge of the board.

Examples

			1, 1, 4/3, 62/43, 269/167, 1766/1017, 395497/213488, 101338/51901, 44125237/21578387, 227721959/106983448, ...
Approximately 1, 1, 1.333, 1.442, 1.611, 1.736, 1.853, 1.953, 2.045, 2.129, 2.206, ...
		

Crossrefs

A376737 are the corresponding denominators.
A376606 and A376607 are similar for a rook walk with unit steps.
A376609 and A376610 are similar for a chess king.

Programs

  • PARI
    \\ Uses function droprob from A376606
    knightmoves = [[2, 1], [1, 2], [-1, 2], [-2, 1], [-2, -1], [-1, -2], [1, -2], [2, -1]];
    a376736(n) = numerator(droprob(n, knightmoves, 8))

A323561 Number of rooted self-avoiding king's walks of n moves on an infinite chessboard with first move specified.

Original entry on oeis.org

2, 14, 92, 584, 3644, 22482, 137626, 837466, 5072590, 30611376, 184171252, 1105262004, 6618842522, 39564403462, 236123357538, 1407249202976, 8376673823516
Offset: 1

Views

Author

Hugo Pfoertner, Jan 17 2019

Keywords

Comments

The first move is either (0,0) -> (1,0) or (0,0) -> (1,1). Rotated paths are not counted separately.

Crossrefs

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

A347363 Number of self-avoiding knight's paths from the lower left corner to the lower right corner of a 3 X n chessboard.

Original entry on oeis.org

1, 0, 2, 8, 32, 156, 871, 5292, 28702, 154162, 845532, 4662014, 25579463, 140098348, 767973001, 4212065280, 23097682805, 126643657272, 694390484065, 3807499106946, 20877386149018, 114474503105178, 627683328355315, 3441701959286326, 18871492466212538
Offset: 1

Views

Author

Andrzej Kukla, Aug 29 2021

Keywords

Comments

If we enumerate the squares in the 3 X n board like this:
------------------------------------
| 1 | 4 | 7 | 10 | 13 | ... | 3n-2 |
------------------------------------
| 2 | 5 | 8 | 11 | 14 | ... | 3n-1 |
------------------------------------
| 3 | 6 | 9 | 12 | 15 | ... | 3n |
------------------------------------
then a(n) is the number of self-avoiding knight's paths on such a board from square 3 to square 3n.

Examples

			For n = 4 we have exactly 8 self-avoiding paths starting at square 3 and ending at square 12:
  3,  4,  9, 10,  5, 12;
  3,  4,  9,  2,  7, 12;
  3,  8,  1,  6,  7, 12;
  3,  4, 11,  6,  7, 12;
  3,  8,  1,  6, 11,  4,  9,  2,  7, 12;
  3,  4, 11,  6,  7,  2,  9, 10,  5, 12;
  3,  8,  1,  6,  7,  2,  9, 10,  5, 12;
  3,  8,  1,  6, 11,  4,  9, 10,  5, 12;
		

Crossrefs

Extensions

a(8)-a(15) from Pontus von Brömssen, Aug 30 2021
Terms a(16) and beyond from Andrew Howroyd, Nov 19 2021
Showing 1-5 of 5 results.