| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 7 |
| 3 | 22 |
| 4 | 61 |
| 5 | 172 |
| 6 | 484 |
| 7 | 1356 |
| 8 | 3800 |
| 9 | 10648 |
| 10 | 29836 |
| 11 | 83601 |
| 12 | 234256 |
| 13 | 656394 |
| 14 | 1839243 |
| 15 | 5153632 |
| 16 | 14440679 |
| 17 | 40463352 |
| 18 | 113379904 |
| 19 | 317694950 |
| 20 | 890193745 |
| 21 | 2494357888 |
| 22 | 6989288906 |
| 23 | 19584262410 |
| 24 | 54875873536 |
| 25 | 153764355951 |
| 26 | 430853773030 |
| 27 | 1207269217792 |
| 28 | 3382815830942 |
[1,2,7,22,61,172,484,1356,3800,10648,29836,83601, 234256,656394,1839243,5153632,14440679,40463352, 113379904,317694950,890193745,2494357888, 6989288906,19584262410,54875873536,153764355951, 430853773030,1207269217792,3382815830942] |