A356404 -id:A356404 - cp's OEIS frontend

A368499 Number of non-congruent simple polygons with 2n sides on the unbounded chessboard such that each side is an edge of the corresponding knight graph.

3, 13, 178, 3034, 64877, 1503790, 36930111

Offset: 2

Kaloyan Kapralov, Dec 27 2023

A knight graph is a graph that represents all legal moves of the knight chess piece on a chessboard. Each vertex of this graph represents a square of the chessboard, and each edge connects two squares that are a knight's move apart from each other.
Two polygons in the knight graph are called congruent if one can be transformed into the other by applying one or more of the operations of translation, rotation, and reflection on the chessboard; otherwise, they are non-congruent.
This sequence, in contrast to A366778, considers only simple, i.e., non-self-intersecting polygons.

			For n=2 the a(2)=3 solutions (in standard chess notation) are:
  (a1,c2,d4,b3), (a2,c1,d2,c3), (a2,c1,d3,b3).
For n=3 the a(3)=13 solutions are:
  (a1,b3,a5,c4,e3,c2), (a1,b3,a5,c6,b4,c2), (a1,b3,a5,c6,d4,c2),
  (a1,b3,c5,e6,d4,c2), (a2,b4,c2,d4,e2,c1), (a2,b4,c6,d4,b3,c1),
  (a2,b4,c6,d4,e2,c1), (a2,b4,c6,e5,d3,c1), (a2,b4,d5,c3,e2,c1),
  (a2,b4,d5,f4,d3,c1), (a2,b4,d5,f4,e2,c1), (a2,c1,d3,f4,d5,c3),
  (a2,c1,e2,g3,e4,c3).

Stoyan Kapralov, Valentin Bakoev, and Kaloyan Kapralov, Algorithms for Construction and Enumeration of Closed Knight's Paths, Mathematics and Informatics, 2, (2023), 107-114; arXiv:2304.00565 [math.CO], 2023.
Kaloyan Kapralov, Example for n=3: the 13 non-congruent simple polygons.

Cf. A366778, A001230, A234623, A254129, A356404.

A366778 Number of nonequivalent cycles of length 2n in the (2n+1) X (2n+1) knight graph.

Original entry on oeis.org

3, 25, 480, 12000, 350256, 10780549, 344680960

Offset: 2

Stoyan Kapralov, Dec 15 2023

A knight graph is a graph that represents all legal moves of the knight chess piece on a chessboard. Each vertex of this graph represents a square of the chessboard, and each edge connects two squares that are a knight's move apart from each other.

Two cycles in the knight graph are called equivalent if one can be obtained from another by applying one or more of the operations of translation, rotation, and symmetry on the chessboard; otherwise, they are nonequivalent.

			For n=2 the a(2)=3 solutions (in standard chess notation) are: (a1, c2, d4, b3), (a2, c1, d2, c3), and (a2, c1, d3, b3).
Note that each of these three cycles is non-self-intersecting. For the remaining values of n there are two kind of cycles - self-intersecting and non-self-intersecting. For example, a self-intersecting cycle of length 6 is (a1, c2, b4, a2, c1, b3), while the cycle (a1, c2, e1, f3, d4, b3) is non-self-intersecting.

Stoyan Kapralov, Valentin Bakoev, and Kaloyan Kapralov, Algorithms for Construction and Enumeration of Closed Knight's Paths, Mathematics and Informatics, 2, (2023), 107-114; arXiv:2304.00565 [math.CO], 2023.

Cf. A368499, A001230, A234623, A254129, A356404.

cp's OEIS Frontend

A368499 Number of non-congruent simple polygons with 2n sides on the unbounded chessboard such that each side is an edge of the corresponding knight graph.

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