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| n | a(n) |
|---|---|
| 0 | 4 |
| 1 | 3 |
| 2 | 6 |
| 3 | 10 |
| 4 | 21 |
| 5 | 46 |
| 6 | 108 |
| 7 | 263 |
| 8 | 658 |
| 9 | 1674 |
| 10 | 4305 |
| 11 | 11146 |
| 12 | 28980 |
| 13 | 75547 |
| 14 | 197262 |
| 15 | 515594 |
| 16 | 1348477 |
| 17 | 3528150 |
| 18 | 9233244 |
| 19 | 24167167 |
| 20 | 63261114 |
| 21 | 165604618 |
| 22 | 433534041 |
| 23 | 1134967250 |
| 24 | 2971318756 |
| 25 | 7778909811 |
| 26 | 20365282518 |
| 27 | 53316730378 |
| 28 | 139584573093 |
| 29 | 365436446014 |
| 30 | 956723886540 |
[4,3,6,10,21,46,108,263,658,1674,4305,11146,28980, 75547,197262,515594,1348477,3528150,9233244, 24167167,63261114,165604618,433534041,1134967250, 2971318756,7778909811,20365282518,53316730378, 139584573093,365436446014,956723886540] |