OEIS Server: https://oeis.org/edit/global/3061

Joerg Arndt: This is a failed attempt to get Peano's curve; non-self-avoiding after the first iterate

Joerg Arndt: Using the maps 1 -> 1,2,1,2,1 2 -> 4,3,4,3,4 3 -> 2,1,2,1,2 4 -> 3,4,3,4,3 gives Peano's curve; not to myself: zrender -d=4 -a=1 -m='1 1,2,1,2,1 2 4,3,4,3,4 3 2,1,2,1,2 4 3,4,3,4,3' -i=5 -A -e=0.1

Joerg Arndt: Not "the" Peano curve (wich is of order 9), but a order 25 curve; the L-system does a sqrt trickery similar to what Dekking does.

Georg Fischer: @Kevin: I was told that, for old sequences, it's preferred to adapt the definition to the data than vice versa .

Kevin Ryde: Yeah. Until Michel added crossrefs, it had a worrying look of off-by-one in the code.

I see the 3x3 Peano would be A105239 in this style, if this had have been Peano. That one's a bit friend-less just at the moment :-).

Joerg Arndt: charpoly is x^4 - 6*x^3 + 5*x^2 - (x-5)*(x-1)*x^2; transition matrix is ... boring