A123936 - OEIS

%I #8 Oct 13 2019 23:02:41

%S 0,0,4,0,41,372,3189,15544,94844,606556,3341926,18243164,100641235,

%T 541792652,2853058729,14909615644,77215251362,395393899688,

%U 2007472847598,10120652405244,50668068245114,252048156500636,1246766824001246,6135236528242698,30045694433419662

%N a(n) = A079137(n)/2.

%C Number of nonequivalent (or geometrically distinct) directed open knight's tours on a 4 X n chessboard up to rotation and reflection. See A328341 for the number of geometrically distinct undirected open knights's tours. - _Andrew Howroyd_, Oct 12 2019

%H Andrew Howroyd, <a href="/A123936/b123936.txt">Table of n, a(n) for n = 1..500</a>

%Y Cf. A079137, A123935, A328341.

%K nonn

%O 1,3

%A _N. J. A. Sloane_, Oct 30 2006

%E Terms a(22) and beyond from _Andrew Howroyd_, Oct 13 2019