Hénon attractor

A two-line map of the plane into itself. Iterate it and the points fall onto a curved band that, under magnification, splits into bands within bands, like the layers of puff pastry.

xₙ₊₁ = 1 − a xₙ² + yₙ, yₙ₊₁ = b xₙ; a = 1.4, b = 0.3

On mathcurve.com as Attracteur de Hénon