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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 5 |
| 3 | 13 |
| 4 | 40 |
| 5 | 134 |
| 6 | 467 |
| 7 | 1671 |
| 8 | 6172 |
| 9 | 23436 |
| 10 | 90370 |
| 11 | 354271 |
| 12 | 1410448 |
| 13 | 5681881 |
| 14 | 23111260 |
| 15 | 94915721 |
| 16 | 393246863 |
| 17 | 1640456796 |
| 18 | 6888518741 |
| 19 | 29110220069 |
| 20 | 123682094892 |
| 21 | 528032933464 |
| 22 | 2264948231740 |
| 23 | 9757427695261 |
| 24 | 42194050729094 |
| 25 | 183120618953859 |
| 26 | 797497306584136 |
| 27 | 3483922404178219 |
| 28 | 15263691795321215 |
[1,2,5,13,40,134,467,1671,6172,23436,90370,354271, 1410448,5681881,23111260,94915721,393246863, 1640456796,6888518741,29110220069,123682094892, 528032933464,2264948231740,9757427695261, 42194050729094,183120618953859,797497306584136, 3483922404178219,15263691795321215] |