Uses two flip-slops to get a 4-state machine, and then just activates LEDs from the outputs.
Set clock to button and click through.
| # | Input | Output |
|---|---|---|
| 0 | clock | segment a |
| 1 | reset | segment b |
| 2 | none | segment c |
| 3 | none | segment d |
| 4 | none | segment e |
| 5 | none | segment f |
| 6 | none | segment g |
| 7 | none | none |