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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 10 |
| 4 | 23 |
| 5 | 66 |
| 6 | 222 |
| 7 | 561 |
| 8 | 1647 |
| 9 | 5410 |
| 10 | 14318 |
| 11 | 42351 |
| 12 | 137018 |
| 13 | 372191 |
| 14 | 1105275 |
| 15 | 3537540 |
| 16 | 9772767 |
| 17 | 29090826 |
| 18 | 92364198 |
| 19 | 258208671 |
| 20 | 769820418 |
| 21 | 2429091885 |
| 22 | 6850744365 |
| 23 | 20447143866 |
| 24 | 64200928194 |
| 25 | 182303186391 |
| 26 | 544550917797 |
| 27 | 1702925802766 |
| 28 | 4861918919447 |
[1,1,3,10,23,66,222,561,1647,5410,14318,42351, 137018,372191,1105275,3537540,9772767,29090826, 92364198,258208671,769820418,2429091885, 6850744365,20447143866,64200928194,182303186391, 544550917797,1702925802766,4861918919447] |