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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 0 |
| 3 | 1 |
| 4 | 1 |
| 5 | 9 |
| 6 | 1 |
| 7 | 127 |
| 8 | 323 |
| 9 | 1515 |
| 10 | 4191 |
| 11 | 10455 |
| 12 | 20705 |
| 13 | 93802 |
| 14 | 113634 |
| 15 | 3219205 |
| 16 | 10626023 |
| 17 | 45980364 |
| 18 | 139604903 |
| 19 | 555857157 |
| 20 | 1334821448 |
| 21 | 7577098816 |
| 22 | 20676558270 |
| 23 | 61994003643 |
| 24 | 193904367362 |
| 25 | 800928670232 |
| 26 | 2374027931492 |
| 27 | 12506574770693 |
| 28 | 29311991924792 |
[1,0,0,1,1,9,1,127,323,1515,4191,10455,20705, 93802,113634,3219205,10626023,45980364,139604903, 555857157,1334821448,7577098816,20676558270, 61994003643,193904367362,800928670232, 2374027931492,12506574770693,29311991924792] |