All 88 ways to draw arrows on a 4×4 grid, moving from node to node. Each node must have an incoming and an outgoing arrow. Arrows must not cross each other. It is akin to placing 16 ants in a grid, each in a cell. These ants must all move to a different cell without crossing each other’s paths. See: https://oeis.org/A216678 and https://projecteuler.net/problem=393.

Arrows and ants, white on black, A3

• 11×8 grid
• 39×28 cm