Hamiltonian cycles on square grids.

[N. J. A. Sloane]

I first want to thank Diana Mecum for calculating more terms of my sequences. (I actually want to thank everybody who extends my sequences.)

After Diana calculated more terms of A141330 through A141335, I used the EIS' plot function on these sequences. And I was rather surprised.

Are the irregular hexagons that appear in the scatterplots of these sequences:
(a) just an interference artifact of the plotting software or of my browser?
Or (b) a result purely of the mathematics of the sequences?

(If the answer is (a), then the plots may very well look different to other people viewing them than they do to me.)

Hopefully the answer is (b), but I doubt it.

Thanks,
Leroy Quet