A328816 Number of semi-magic (only short lines are magic) knight's tours on a 4 X 2n board.

0, 0, 0, 16, 104, 608, 3480, 19212, 213280, 587072, 3237456

Offset

1,4

Links

Table of n, a(n) for n=1..11.

G. P. Jelliss, Oblong Magic Knight Tours

Awani Kumar, Studies in Tours of Knight on Rectangular Boards, arXiv:1802.09340 [math.GM], 2018.

Formula

a(n) = A309273(2*n).

Example

Example of a 4 X 10 semi-magic knight's tour (only the short lines are magic):
   +----+----+----+----+----+----+----+----+----+----+
   |  1 | 38 |  3 | 24 |  5 | 34 |  9 | 26 | 13 | 30 |
   +----+----+----+----+----+----+----+----+----+----+
   | 20 | 23 | 18 | 37 |  8 | 25 |  6 | 29 | 10 | 27 |
   +----+----+----+----+----+----+----+----+----+----+
   | 39 |  2 | 21 |  4 | 33 | 16 | 35 | 12 | 31 | 14 |
   +----+----+----+----+----+----+----+----+----+----+
   | 22 | 19 | 40 | 17 | 36 |  7 | 32 | 15 | 28 | 11 |
   +----+----+----+----+----+----+----+----+----+----+

Crossrefs

Cf. A309273, A309271.

Sequence in context: A186852 A010079 A022708 * A146211 A258636 A195806

Adjacent sequences: A328813 A328814 A328815 * A328817 A328818 A328819

Keyword

nonn,more

Author

Awani Kumar, Oct 28 2019

Status

approved