[seqfan] Re: Wanted: suggestions of new sequences for poster

[Kevin Ryde]

guninski at guninski.com (Georgi Guninski) writes:
>
> a(n)=x^2+y^2 mod 2^11 gives circles both in grayscale and
> colormap prism_r.

You can get a similar effect by taking x,y points in order of increasing
distance from the origin, ie. increasing x^2+y^2, and from the index n
plot n mod 100 (or whatever) as a colour.  The effect breaks down at a
certain distance away from the origin.  Things vaguely related to a
modulus such as digit product A007954 give circles too.

I'm not sure if there's sequences for x,y coordinates in this order.
I didn't find ones for a full plane positive+negative or for an
eighth 0<=Y<=X.  For full plane the index n on the x axis is A051132
counting from n=0 at the origin.