| n | a(n) |
|---|---|
| 1 | 4 |
| 2 | 16 |
| 3 | 58 |
| 4 | 208 |
| 5 | 748 |
| 6 | 2692 |
| 7 | 9688 |
| 8 | 34864 |
| 9 | 125464 |
| 10 | 451504 |
| 11 | 1624816 |
| 12 | 5847184 |
| 13 | 21042112 |
| 14 | 75723712 |
| 15 | 272504992 |
| 16 | 980656768 |
| 17 | 3529064512 |
| 18 | 12699954496 |
| 19 | 45703002496 |
| 20 | 164470230016 |
| 21 | 591874824064 |
| 22 | 2129964841216 |
| 23 | 7665050176768 |
| 24 | 27584020672768 |
[4,16,58,208,748,2692,9688,34864,125464,451504, 1624816,5847184,21042112,75723712,272504992, 980656768,3529064512,12699954496,45703002496, 164470230016,591874824064,2129964841216, 7665050176768,27584020672768] |