[seqfan] Hamiltonian cycles on n X m square grid of points.

[Robert FERREOL]

Hello,

On https://oeis.org/A003763  are counted the Hamiltonian cycles on 2n X 
2n  square grid of points

and on https://oeis.org/A222200  the case n+1 X n

It's missing the general case n X m ..

I did this research , but UP TO SYMMETRIES :

Case 2 X 2 : 1

Case 3 X 2 : 1

Case 3 X 3 : 0

Case 4 X 3 : 1 :

Case 4 X 4 : 2 : and

Case 5 X 2 :


Case 5 X 3 :  0


Case 5 X 4 :   5

Case 5 X 5 : 0

Case 6 X 2 : 1 (obvious)

Case 6 X 3 :   2


Case : 6 X 4 :  15 :

ase : 6 X 5 : 44 :

Case : 6 X 6 :  ????   > A003763(3)/8=134 ....


Could I begin a new sequence ???



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ROBERT FERRÉOL
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